OaKST 


Ly  1 JU  l\.  * 

OF  THE 

U N 1VER.S1TY 
or  ILLINOIS 


771 

T254 


Return  this  book  on  or  before  the 
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1972 

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DEC  10 

1954 

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«72 

L161— H41 

Digitized  by  the  Internet  Archive 
in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


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If 


DARK  ROOM 
WORK 


A PRACTICAL  DARK  ROOM  MANUAL,  WITH 
SUGGESTIONS  AS  TO  EQUIPMENT; 
WORKING  CONVENIENCES; 

SHORT  CUTS  AND  HANDY 
METHODS  OF 
DARK  ROOM 
WORK 


TENNANT  AND  WARD 

NEW  YORK 


Copyright  1912  by 

TENNANT  AND  WARD,  NEW  YORK 


CONTENTS 


V7  / 
TZSd 


Chapter  I 

WORKING  SPACE;  VENTILATION  AND  CLEANLINESS 
Chapter  II 

THE  ILLUMINATION  OF  THE  DARK  ROOM 
Chapter  III 

WORK  TABLES;  TRAY  CUPBOARD;  PLATE  CARRIERS 


s 

n 


Chapter  IV 

WATER  SUPPLY;  TAP  FITTINGS;  TUBES  AND  RODS; 
LABELS 

Chapter  V 

FILTERING  SOLUTIONS;  FILTER  PAPERS  AND  STANDS 


Chapter  VI 


CORKS  AND  BOTTLES 


Chapter  VII 

A TRAY  ROCKER;  PLATE  LIFTERS;  WEIGHING  AND 
MEASURING 


Chapter  VIII 

METHODS  OF  MAKING  SOLUTIONS 


Chapter  IX 

FACTS  ABOUT  CHEMICALS 
Chapter  X 

WASHING  AND  DRYING  PLATES  AND  PAPERS 


Chapter  I 


WORKING  SPACE;  VENTILATION 
AND  CLEANLINESS 

JUST  as  surely  as  necessity  is  the  mother  of  in- 
vention and  inconvenience  the  progenitor  of 
expediency,  so,  sooner  or  later,  do  we  all — who 
pursue  elusive  sunbeams  and  fantastic  shadows  under 
the  ruby  lamp — become  prolific  inventors  or  artful 
dodgers.  It  could  not  be  otherwise;  photography 
confronts  us  with  so  many  necessities  to  be  provided 
for — or  dodged!  No  matter  how  simply  the  novice 
begins,  or  how  fore-thoughtful  the  expert  be,  they 
meet  at  last  in  the  inevitable  resort,  dodging  and  con- 
triving in  ways  innumerable  to  make  means  fit  their 
ends.  Probably  this  is  true  of  all  craftsmen,  but 
certainly  in  photography  the  individual  worker  speedily 
becomes  a law  unto  himself,  devising  expedients  and 
modifying  methods  to  suit  his  own  peculiar  needs. 
And  every  man’s  necessities  are  slightly  different  from 
those  of  his  neighbor!  Out  of  these  spontaneous  and 
temporary  expedients  come,  now  and  again,  the  happy 
dodges  which  enable  us  to  make  sport  of  necessity. 
Then  one  day  a friend  comes  along,  who,  seeing  the 
dodge  in  practical  operation,  exclaims:  “Splendid 
idea!  Just  the  thing  for  its  purpose.  Why  do  you  not 
patent  it — or  publish  it.^”  A thousand  dodges  of  this 

5 


DARK-ROOM  WORK 


sort  are  recalled  as  I write:  the  pointed  thimble  serv- 
ing as  a plate  lifter,  the  corrugated  finger-tip  which 
grips,  the  plug  of  cotton-wool  pulled  halfway  into  a bit 
of  glass  tubing  to  form  “Buckle’s  brush,”  and  a host  of 
similar  trifles  which,  like  a drop  of  oil,  make  the  wheels 
go  round  more  easily  and  without  friction. 

Here  we  have  the  purpose  of  this  little  book;  to 
gather  together  a ready  reference  cyclopedia  for  the 
dark-room  worker;  short  cuts,  methods  and  ways  of 
doing  things  and  home-made  contrivances  or  “tips” 
which  may  serve  in  an  emergency  to  take  the  place 
of  more  elaborate  conveniences.  For  the  most  part 
a few  pence,  a little  leisure  and  such  handy  tools  as 
may  be  found  in  the  home  will  suflSce  for  their  making. 
And  this  is  worth  noting,  they  are  all  practical  dodges, 
being  largely  contrived  by  an  artful  dodger  for  his 
own  use;  or  “lifted”  from  the  notebooks  of  other 
worthy  dodgers;  or  seen  in  the  rose-red  light  of  other 
dark-rooms.  It  is  needless  to  add  that  all  dodges  should 
be  taken  as  they  are  given,  in  the  indicative  rather 
than  in  the  imperative  mood. 

In  constructing  a convenient  dark-room  we  require 
size  suflScient  to  allow  the  various  operations  to  be 
conducted  without  overlapping,  and  no  more.  A 
room  which  will  give  space  for  a worker  without 
cramping  him,  after  a sixteen-inch  shelf  has  been  run 
around  three  sides  of  it,  is  suflficiently  large,  and  except 
for  ventilation,  no  advantage  is  to  be  gained  by  increas- 
ing its  size.  We  require  a good  sink  and  water  supply, 
a safe  light,  adequate  ventilation,  heat  in  winter, 
working  benches,  and  racks  and  shelves  for  holding 
bottles  and  trays.  As  for  actual  size,  if  the  room  is 

6 


DARK-ROOM  WORK 


never  occupied  by  more  than  one  worker  at  a time, 
about  seven  by  five  feet  would  not  be  too  small — 
though  one  larger  would  be  preferable;  this  would 
give  a working  space  of  about  five  and  a half  by  two 
and  a half  feet;  or  four  and  a half  by  three  and  a half 
according  to  whether  the  double  row  of  benches  ran 
the  long  or  the  short  way  of  the  room.  Often  the 
dark-room  is  partitioned  off  from  some  other  room, 
and  is  long  and  narrow,  with  the  sink  and  shelves 
running  along  one  side  only.  This  is  a convenient 
arrangement.  In  speaking  of  a room  of  small  size 
it  must  be  remembered  that  we  are  speaking  only 
of  a dark-room,  not  of  a work  or  store  room.  The 
dark-room  should  not  be  used  as  a general  store- 
room, for  chemical  fumes  or  heat  may  have  a dele- 
terious action  on  stock.  Much  of  the  writer’s  dark- 
room work  has  been  done  in  a closet  measuring  about 
five  feet  by  thirty-three  inches,  but  possessing  the 
great  advantage  of  a porcelain  bowl  with  running 
water;  and  many  workers  will,  like  him,  be  bound 
by  actual  rather  than  by  ideal  conditions. 

It  is  not  possible  to  give  any  actual  dimensions 
for  a room.  Many  photographers  never  handle  larger 
sizes  than  8 x 10,  while  the-  greater  proportion  of  their 
work  is  smaller.  Where  sizes  up  to  17  x 22  are  handled, 
the  minimum  size  suggested  above  would  be  quite  inade- 
quate. The  door  needs  some  consideration.  In  a 
small  dark-room  such  as  we  refer  to,  the  photographer 
would  probably  close  and  bolt  his  door  after  him, 
and  if  he  needed  to  leave  during  development  would 
cover  his  tray  and  leave  his  plate  in  darkness;  but 
with  a room  which  is  regularly  used,  and  in  and  out 

7 


DARK-ROOM  WORK 


of  which  people  may  require  to  pass,  some  other  ar- 
rangement is  needed,  such  as  two  doors  with  a suffi- 
cient space  between  them,  so  that  a man  may  close 
one  behind  him  before  opening  the  other.  Another 
way,  preferable,  where  people  are  constantly  passing 
in  and  out,  is  to  have  no  door  at  all,  but  a short  pas- 
sage constructed  with  light  traps.  Wings  are  run 
about  two-thirds  of  the  way  across  the  passage,  alter- 
nately from  the  left  and  the  right;  these  are  colored 
dead  black,  and  four  of  them  will  prove  as  efficient 
a light  trap  as  is  needed. 

That  the  dark-room  should  be  kept  free  from  dust 
is  a precept  which  needs  no  emphasis  here.  In  these 
days  of  dry-plates  and  films  the  problem  of  keeping 
dust  out  of  the  dark-room  and,  at  the  same  time, 
securing  abundant  ventilation,  has  brought  forth 
many  inventions.  The  plan  I adopted  in  my  base- 
ment dark-room  years  ago  has  proved  as  efficient  as 
it  was  simple.  Procuring,  from  a neighboring  plumber, 
twelve  pieces  of  IJ^-inch  lead  piping,  each  piece  seven 
inches  in  length,  I bent  these  to  form  a right-angled 
tube  similar  to  B in  Fig.  8,  except  that  the  bend  was 
about  two  inches  from  one  end.  These  tubes  I lined 
with  coarse  felt  or  flannel,  LePage’s  glue  serving  as 
the  adhesive.  Next,  this  felt  lining  was  saturated  with 
linseed  oil.  Six  of  these  tubes  were  snugly  fitted  into 
holes  bored  through  the  dark-room  door,  about  five 
inches  from  the  floor,  the  long  arm  of  each  tube 
hanging  free  within  an  inch  or  so  of  the  floor  inside 
the  room.  On  the  outside  of  the  door  I fixed  a strip 
of  wire-net,  to  cover  the  circular  apertures,  admitting 
air  from  the  passageway.  The  other  six  tubes  were 

8 


DARK-ROOM  WORK 


similarly  fixed  into  a wood  panel  above  the  dark- 
room window,  thus  communicating  with  the  free  air 
out-of-doors.  In  this  case,  however,  the  long  arm  of 
each  tube  was  turned  to  the  ceiling.  By  this  simple 
dodge,  which  occupied  a spare  afternoon,  I secured 
abundant  ventilation,  freedom  from  that  musty 
dampness  peculiar  to  basement  dark-rooms,  and  a 
minimum  of  dust,  the  air  passing  through  tubes  lined 
with  oiled  felt.  The  tubes  should  be  removed  three 
or  four  times  yearly,  and  the  felt  re-oiled;  but  beyond 
this  slight  trouble  the  system  has  given  perfect  satis- 
faction. The  walls  and  shelves  of  the  dark-room  should 
be  coated  with  a waterproof  paint,  such  as  Probus. 

Keeping  a dark-room  clean  is  an  elementary  detail, 
but  is  often  an  unsuspected  source  of  trouble.  I have 
often  wondered  to  see  otherwise  intelligent  workers 
dust  down  their  shelves  and  tables,  and  then  begin 
to  change  their  plates  or  develop  a batch  of  exposures. 
This  is  beginning  at  the  wrong  end.  Dusting  the  dark- 
room should  be  done  at  night  just  before  closing,  or 
at  least  a few  hours  before  any  photographic  work  is 
attempted.  When  any  dark-room  work  is  on  hand, 
take  time  by  the  forelock.  Early  in  the  morning  take 
a slightly  damp  cloth  or  mop  and  gather  up  the  dust 
from  shelves,  table  and  floor.  Follow  this  with  a dry 
cloth,  and  then  let  the  room  be  closed  for  an  hour  or 
two  at  least.  With  this  simple  precaution,  the  reader 
may  at  all  times  be  confident  that  dust  will  not  trouble 
him  in  the  operations  of  changing  or  developing  his 
plates. 

It  has  been  my  practice  for  a long  time  to  dust  my 
plates  in  the  holder.  This  I do  by  drawing  out  the 

9 


DARK-ROOM  WORK 


slide  and  then  slowly  and  lightly  passing  a dry,  broad 
and  soft  camel’s-hair  brush  over  the  film.  In  the 
wooden  handle  of  the  brush  is  a hole,  and  through  this 
a loop  of  elastic.  This  loop  conveniently  goes  over 
the  top  button  of  my  coat,  so  that  I do  not  need  to 
put  down  the  brush  on  a dirty  table  or  wet  shelf  during 
the  operation.  The  loop  also  serves  to  hang  up  the 
brush  on  a nail  at  the  end  of  a shelf  opposite  the  dark- 
room lamp,  so  that  it  can  readily  be  seen  in  a dim 
light.  For  large  plates  I prefer  a home-made  brush, 
as  shown  in  Fig.  1.  This 
consists  of  an  old  film  bent 
over  to  bring  edge  to  edge, 
covered  with  silk  velvet,  the 
two  ends  being  fixed  to  a 
bit  of  cigar-box  for  a handle. 

One  point  to  remember  when  dusting  plates  is  that 
if  you  quickly  rub  the  film  with  the  duster  you 
charge  the  surface  with  electricity,  and  this  tends  to 
attract  particles  of  dust.  This  point  can  be  demon- 
strated by  briskly  rubbing  a bit  of  clean  glass  with  a 
bit  of  silk  and  then  holding  it  half  an  inch  away  from 
some  tiny  particles  of  paper. 

Plate-holders,  dark  slides,  or  whatever  you  please 
to  call  them,  require  cleaning  out  occasionally.  This 
is  best  done  in  daylight.  At  the  same  time  see  that 
the  slides  draw  in  and  out  easily.  If  not,  ease  them 
with  a little  dry  black  lead  or  soft  graphite.  A fairly 
soft  pencil  is  convenient  for  this  purpose,  and  enables 
one  to  get  into  the  corners  and  grooves.  On  no 
account  use  oil,  grease,  or  anything  of  that  kind. 

The  dark-room  lamp  is  an  item  of  considerable  im- 
10 


ov^xunmnifiintfirf, 

V"  ’ll', '(A 

it  i 


DARK-ROOM  WORK 


portance,  and  a few  words  about  the  form  which  I 
have  worked  up  to  may  be  suggestive.  There  are 
innumerable  patterns  buyable  at  all  prices,  yet  I 
found  it  cheapest  to  have  made  for  me  the  one  I have 
now  had  in  satisfactory  use  for  some  years.  It  consists 
of  a tin  box  roughly  12  inches  high,  12  inches  wide,  and 
6 inches  from  back  to  front.  The  parts  are  fixed 
together  by  over-lapping  joints,  strengthened  by 

rivets  in  case  of  the  solder 
giving  way.  Light  is 
trapped  in  the  usual  way. 
The  front  contains  two 
grooves,  the  outer  one 
wide  enough  to  easily 
hold  three  sheets  of 
ordinary  glass  loosely. 
The  inner  groove  is 
about  half  this  width. 
A glance  at  Fig.  2 (not 
drawn  to  scale)  will  show 
how  these  two  grooves 
may  be  used  to  hold 
sheets  of  colored  glass.  I find  a gas  fiame  the  most 
convenient  light,  inside  the  box,  which  is  fixed  to 
the  wall  to  my  left,  over  the  sink.  Inside  the  box 
and  behind  the  flame  is  a sheet  of  white  pot  or  flashed 
opal  glass.  This  acts  as  a reflector;  and  a sponge  and 
soap  will  clean  it  in  a minute.  Next  comes  a sheet  of 
fine  ground  glass  (dotted  in  the  diagram)  in  the  inner 
groove;  and  in  the  outer  groove  one  or  more  sheets 
of  colored  glass,  according  to  my  needs.  For  bromide 
paper  and  lantern  plates  I find  a sheet  of  orange  glass 

11 


U.  OF  III.  1-‘B 


DARK-ROOM  WORK 


quite  safe  with  ordinary  care,  For  ordinary  plates  I 
replace  this  by  a sheet  of  ruby  glass.  For  more  sensi- 
tive plates  the  orange  and  ruby  glass  are  used  together, 
or  any  other  combination  of  “safe  lights”  required 
for  the  manipulation  of  the  particular  plates  in  use. 


12 


Chapter  II 


ILLUMINATION  OF  THE  DARK-ROOM 

Much  depends  upon  the  correct  lighting 
of  the  dark-room.  There  are  two  main 
factors  to  be  considered — the  safety  of  the 
light  as  towards  sensitive  films,  and  the  worker’s 
comfort.  This  latter  factor  has  too  often  been  over- 
looked. To  obtain  “safety”  photographers  have  been 
content  to  work  with  the  dimmest  of  dull  lights.  A 
glimmer  through  a deep  ruby  glass  is  one  of  the  com- 
monest mistakes;  for  it  is  quite  possible  to  combine 
safety  with  a fair  volume  of  light;  and  light  of  a tint 
which  does  not  affect  the  eyes  unpleasantly.  The 
light  may  be  either  day  or  artificial.  One  disad- 
vantage urged  against  the  former,  by  those  who  can 
do  their  work  during  daylight,  is  that  it  is  variable 
in  intensity,  but  this  argument  is  valid  only  with 
those  who  closely  examine  their  negatives  from  time 
to  time  during  development,  to  judge  density,  a custom 
which  is  largely  dying  out.  In  regard  to  a “safe” 
light,  it  is  much  a question  of  how  close  and  for  how 
long  a time  the  plate  is  held  to  it.  A light  that  illumines 
the  dark-room  so  that  every  bottle  and  package  can 
be  seen,  would  probably  be  safe,  if  the  plate  to  be 
developed  were  taken  from  its  holder  and  at  once 
placed  in  the  developer  and  covered  over;  but  the 
same  plate  might  fog  if  the  developing  tray  were  held 

13 


DARK-ROOM  WORK 


close  to  a much  weaker  light,  in  an  endeavor  to  see 
the  first  indication  of  any  image. 

For  orthochromatic  plates  I use  a triple  screen  of 
aurantia,  naphthol  yellow  and  methyl  violet  6B.  The 
easiest  plan  to  prepare  these  is  to  fix  and  wash  three 
unexposed  ordinary  plates,  so  as  to  obtain  glasses 
coated  with  clear  gelatine,  and  then  soak  them  in 
aqueous  solutions  of  these  dyes.  It  is  not  every 
amateur,  however,  who  finds  it  convenient  to  buy  a 
box  of  12  X 15  plates  in  order  to  get  three  sheets  of 
glass  a foot  square  coated  with  gelatine.  I tried  this 
plan,  but  found  the  gelatine  coating  so  thin  that  it 
did  not  hold  a sufficient  quantity  of  dye.  My  next 
plan  was  to  obtain  three  pieces  of  ordinary  clear  glass 
12  X 12  inches.  These  were  thoroughly  cleaned.  A 
fiat  drawing  board  was  carefully  leveled  with  the  aid 
of  three  wedges  underneath.  A glass  ball  about  the 
size  of  a hen’s  egg  (costing  a few  cents  at  the  toy  shop) 
soon  helps  one  to  get  the  board  level,  as  it  always  rolls 
toward  the  lower  side  of  the  board.  I now  take  15 
to  20  grains  of  shredded  gelatine  (Nelson’s)  and  soak 
this  in  one  ounce  of  a cold  saturated  aqueous  solution 
of  aurantia.  When  the  gelatine  is  quite  swelled,  the 
containing  vessel  is  put  into  a pan  of  warm  water  and 
the  gelatinous  mass  gently  heated.  Meanwhile  the 
glass  plate  to  be  coated  is  slightly  warmed.  Then  the 
aurantia-gelatine  solution  is  poured  on  the  warmed 
glass  plate  laid  on  a sheet  of  paper  on  the  level  drawing 
board.  A glass  rod  enables  us  to  guide  the  liquid. 
The  plate  being  warmed  keeps  the  mixture  fiuid  for 
some  little  time,  and  so  gives  plenty  of  time  to  slowly 
add  the  coating  and  lead  it  to  the  edges  of  the  plate. 

14 


DARK-ROOM  WORK 


It  is  then  allowed  to  set  and  dry  in  this  horizontal 
position.  In  the  same  way  we  use  gelatine  and  a cold 
saturated  solution  of  naphthol  yellow  for  our  second 
plate.  For  the  third  plate  we  do  not  need  a saturated 
solution  of  methyl  violet  6B,  but  one  which  is  so  strong 
that  one  drop  seen  by  transmitted  light  on  a glass 
plate  is  a fairly  deep  violet.  In  this  way  I found  I 
got  much  more  of  the  two  yellow  dyes.  If  the  violet 
screen  dries  too  dark  it  can  be  lightened  by  washing 
in  cold  water.  If  not  dark  enough  it  can  be  darkened 
after  drying  by  pouring  over  its  surface  a stronger 
solution  and  allowing  it  to  soak  in.  These  three  plates, 
when  put  together,  permit  only  a narrow  band  in  the 
far  red  end  of  the  spectrum  to  pass.  In  this  light  the 
most  sensitive  orthochromatic  plate  may  be  developed. 
This  set  of  dyes  has  been  published  before,  but  they 
are  so  very  important  and  of  such  great  value  that 
their  repetition  here  may  be  helpful. 

A window  may  be  utilized  by  glazing  it  with  colored 
glass,  or  by  covering  the  clear  glass  with  colored  paper 
or  fabric.  The  fabric  may  be  pasted  on  the  glass,  or, 
preferably,  mounted  on  a frame  to  fit  the  window. 
This  frame  should  be  made  of  light,  flat  laths,  and  just 
large  enough  to  fit  snugly  over  the  window  sash,  close 
to  the  panes.  With  a couple  of  staples  at  the  top  of 
the  window  for  the  edge  of  the  frame  to  be  slipped 
under,  and  a turn  button  at  the  bottom  to  hold  it 
lightly  in  place,  it  can  be  put  up  in  a moment.  A strip 
of  thick  felt  tacked  along  the  edges  of  the  frame  will 
provide  against  shrinkage  and  ensure  a snug  fit  in 
the  window  casing.  A common  mistake  is  made  of 
entirely  blocking  the  greater  portion  of  a window, 

15 


DARK-ROOM  WORK 


leaving  a small  opening  of  perhaps  a foot  square;  it 
would  be  more  comfortable  to  have  the  opening  two 
or  even  three  feet  square,  and  this  is  quite  feasible  if 
a suitable  medium  is  used. 

In  my  present  dark-room  I have  a rather  large 
window,  e.  g.,  about  4 feet  by  6 feet.  And  as  I use 
the  same  room  for  other  purposes,  I wish  to  have  a 
daylight-room  or  dark-room  at  will.  A light  wooden 
framework  was  made  to  fit  the  recess  of  the  window. 
The  frame  is  very  ^ 

similar  to  that  used 
for  “stretchers”  for 
canvas  for  oil  paint- 
ing. So  that  if  the 
reader  is  not  very 
handy  with  his  fingers, 
for  a quite  small  cost 
he  can  order  to  be 
made  a canvas 
stretcher  at  any  shop 
where  artists’  materials  are  sold.  In  my  case  this 
frame  was  first  covered  over  with  cotton  sheeting, 
folded  over  the  edge  and  fixed  by  tacks,  as  suggested 
in  Fig.  3.  The  sheeting  was  then  covered  by  a couple 
of  thicknesses  of  somewhat  thin,  yet  tough,  opaque 
parcel  brown  paper.  I find  this  quite  opaque  to  day- 
light. Two  smalt  blocks,  A and  A,  were  screwed  on 
the  window-frame  so  that  the  shutter,  as  we  may  now 
call  it,  just  rested  on  them.  Two  other  side  blocks  at 
B and  B kept  it  in  position.  To  each  of  the  four 
blocks  I put  a flat  wooden  “turn  button.”  In  the 
lower  corner  of  Fig.  3 is  shown  a diagram  section  of  the 

16 


DARK-ROOM  WORK 


turn  button  and  block.  It  should  be  noticed  that  the 
lower  side  of  the  tongue  of  the  turn  button  is  slightly 
chamfered  away.  If  this  is  not  done,  you  will  find 
your  turn  buttons  constantly  catching  and  tearing 
the  sheeting  or  getting  jammed  with  the  nails  holding 
down  the  sheeting. 

It  may  be  useful  to  know  how  to  test  the  safety  of 
the  dark-room  lamp  or  window,  lest  our  plates  fog 
with  overmuch  light,  for  there  is  ruby 
glass  and  ruby  glass.  The  eye  fails  to 
tell  us  which  is  safe  and  which  is  unsafe. 
Moreover,  plates  vary  in  their  sensi- 
tiveness. And,  again,  it  may  be  safe 
to  expose  a certain  plate  to  a light, 
for  say,  one  minute  and  yet  unsafe  to 
expose  it  to  the  same  light  for  ten 
minutes.  To  test  this  the  “strip  test” 
method  is  useful  and  easily  made.  Take 
a strip  of  card  the  same  length  as  that 
of  the  plate  to  be  used  in  testing.  Cut 
this  into  a stepshaped  piece  like  Fig. 
4,  having  as  many  equal  steps  as  you 
wish  your  test  plate  to  register  (in  this 
case  five  steps).  Put  the  plate  into 
an  ordinary  plate-holder  in  the  usual 
way,  but  do  this  well  away  from  the  dark-room  lamp 
and  under  cover  of  the  focusing  cloth.  Have  a 
friend  at  hand  to  time  the  minutes  with  a watch. 
Now  go  up  to  the  developing  table.  Draw  out 
the  shutter  and  expose  the  plate  to  the  lamp  as 
though  developing  it  for  one  minute.  Then  push 
in  the  shutter  just  the  length  of  one  step  (marked  1). 

17 


DARK-ROOM  WORK 


Expose  for  one  more  minute  and  push  in  as  far  as  the 
second  step  (marked  also  1).  Then  expose  for  two 
minutes  and  push  in  again  as  far  as  the  third  step. 
Similarly  give  the  four-  and  eight-minute  exposures, 
according  to  the  times  marked  on  the  step.  A mo- 
ment’s thought  will  show  that  the  plate  has  had  five 
different  exposures — of  one,  two,  four,  eight  and  six- 
teen minutes.  Develop  as  usual,  but  keep  the  dish 
covered  all  the  time;  fix,  wash  and  dry.  Now  lay  the 
plate,  film  side  down,  on  a sheet  of  white  paper.  You 
can  then  easily  see  the  strip  first  to  show  a difference 
between  the  edge  of  the  plate  protected  by  the  rebate 
of  the  plate-holder  (hence  the  reason  for  changing  the 
slide  in  the  dark).  Such  a test  will  tell  you,  perhaps, 
that  a two-minute  exposure  to  the  dark-room  lamp 
just  begins  to  show  signs  of  light  fog  and  that  four 
minutes  is  serious.  You  will,  therefore,  conclude  that 
during  development  your  developing  dish  should  be 
kept  covered  over  most  of  the  time,  and  that  the  total 
time  of  uncovering  the  plate  for  examination  of  the 
progress  of  development  should  not  exceed  the  time 
your  test  plate  indicates  as  the  practical  safe  time 
limit.  I lay  some  stress  on  this  strip-testing  method, 
both  for  plates  and  bromide  papers  and  slides.  Two 
points  should  be  noted.  If  we  are  working  with  a 
rapid  bromide  paper,  e.  g.,  enlarging,  the  light  may  be 
just  sufficiently  unsafe  to  give  a very  slight  fog  which 
is  not  noticeable  in  the  yellow  light,  and  especially 
when  the  paper  is  wet,  but  is  seen  when  the  paper  is 
dry.  Similarly,  when  making  slides  a very  slight  fog 
veil  may  not  be  seen  until  the  slide  is  examined  against 
a white  background. 


18 


DARK-ROOM  WORK 


Three  kinds  of  tray-covers  are  useful,  according  to 
circumstances.  First,  thin  pieces  of  wood  about  half 
an  inch  or  an  inch  larger  than  the  top  of  the  dish.  I 
have  several  of  suitable  sizes  standing  on  edge  by  the 
sink  side.  These  are  cut  from  the  ordinary  backing 
boards  used  to  back  picture-frames.  They  are  used 
simply  to  cover  the  dish  as  an  extra  precaution  when 
developing.  But  if  I want  to  turn  up  the  naked  gas 
flame  to  And  a bottle  or  graduate  during  development, 
these  flat  wooden  lids  are  not  safe.  In  that  case  I 
use  a stout  cardboard  lid,  e.  g.,  the  lid  of  a half-plate 
box  for  a quarter-plate  developing  tray.  This  card- 
lid  has  a coat  of  black  enamel  paint  inside  and  out, 
to  make  it  proof  against  light  and  to  protect  it  from 
the  effects  of  splashing  liquids.  A third  form  of  pro- 
tection when  the  light  is  to  be  turned  up  for  any  length 
of  time  is  needed.  In  that  case  I put  the  tray  into  a 
cardboard  box  with  a lid. 

It  is  a good  plan  to  number  every  plate  used.  This 
may  be  easily  done  on  the  dry  film  by  the  aid  of  a fine- 
pointed,  rather  hard  pencil.  If  this  number  is  written 
in  the  right-hand  lower  corner,  as  the  plate  is  film 
facing  you  in  the  plate-holder,  with  the  shutter  drawn 
out  to  your  right  for  dusting,  it  will  always  come  in 
the  foreground  (not  sky),  whether  the  plate  be  ex- 
posed for  a horizontal  or  vertical  view.  In  that  case 
the  pencil  number  never  shows  when  the  plate  is 
printed.  Do  not  attempt  to  number  a plate  when  the 
film  is  wet;  a torn  film  is  the  probable  result.  This 
pencil  number  is  not  very  readily  seen,  however,  and 
if  the  plate  gets  much  rubbing  it  may  get  rubbed  out. 
Hence,  as  soon  as  the  plate  is  developed  and  dried  it 

19 


DARK-ROOM  WORK 


should  be  re-numbered  with  water-proof  ink,  written 
with  a fine-point  steel  pen.  It  can  then  be  reduced, 
intensified,  etc.,  without  any  harm,  as  the  ink  is  not 
affected  by  most  of  the  aqueous  solutions  we  use  for 
such  purposes.  If,  however,  we  wish  to  remove  the 
water-proof  ink  at  any  time,  it  can  easily  be  done  with 
a little  methylated  spirit,  applied  with  a bit  of  clean 
rag.  Higgins’  water-proof  India  ink  is  excellent  for 
this  purpose.  Where  such  an  ink  is  not  handy  the 
dry  negative  can  be  numbered  at  the  extreme  edge 
with  a sharp-pointed  tool,  which  will  cut  the  number 
clean  through  the  film  to  the  glass.  Usually  the  nega- 
tive has  a rebate  strip  which  offers  place  for  this 
method  of  numbering. 

Dust  on  the  film  may  arise  from  the  grinding  of  the 
sharp  edge  of  the  glass  plate  against  the  wood  of  the 
plate-holder.  This  is  liable  to  arise  when  the  apparatus 
has  been  well  shaken  on  an  auto  or  train  trip.  In 
such  cases  the  following  dodge  should  be  applied  before 
exposure,  otherwise  the  negative  will  show  dust  pin- 
holes after  development.  Hold  the  plate-holder  by 
one  hand  in  a vertical  position  and  give  it  two  or 
three  sharp  raps  on  its  lower  edge  upon  the  palm  of 
the  other  hand.  This  will  probably  dislodge  the  fine 
particles  adhering  to  the  film  surface  and  cause  them 
to  fall  to  the  lower  edge  of  the  plate.  Of  course,  this 
lower  edge  will  be  the  long  or  short  side,  according 
as  you  are  about  to  take  a horizontal  or  vertical  picture. 


20 


Chapter  III 


WORK  TABLES  AND  TRAY  CUP- 
BOARD; PLATE  CARRIERS 

The  work-table  used  in  the  dark-room  is  liable 
to  become  soiled  and  unsightly  by  the  constant 
action  of  chemical  solutions.  To  avoid  this, 
it  is  well  to  prepare  the  top  of  the  table  in  such  a way 
as  to  render  it  impervious  to  the  action  of  acids  and 
alkalies.  A writer  in  the  Journal  of  Applied  Micro- 
scopy tells  how  to  accomplish  this,  and  I quote  from 
his  paper  as  follows: 

“Prepare  the  following  solutions:  1.  Iron  sulphate, 
4 parts;  copper  sulphate,  4 parts;  potassium  perman- 
ganate, 8 parts;  water,  q.  s.,  100  parts.  2.  Aniline, 
parts;  hydrochloric  acid,  18  parts;  water,  q.  s., 
100  parts,  or  aniline  hydrochlorate,  15  parts;  water, 
q.  s.,  100  parts. 

By  the  use  of  a brush,  two  coats  of  solution  No.  1 
are  applied  while  hot,  the  second  coat  as  soon  as  the 
first  is  dry.  After  solution  No.  1 has  dried,  the  excess 
of  solution  which  has  dried  upon  the  surface  of  the 
wood  is  thoroughly  rubbed  off  before  the  application 
of  solution  No.  2.  Then  two  coats  of  solution  No.  2, 
and  the  wood  allowed  to  dry  thoroughly.  The  black 
color  does  not  appear  at  once,  but  usually  requires 
a few  hours  before  becoming  ebony  black.  Later  a 

21 


DARK-ROOM  WORK 


coat  of  raw  linseed  oil  is  to  be  applied,  using  a cloth 
instead  of  a brush,  in  order  to  get  a thinner  coat  of 
the  oil.  The  linseed  oil  may  be  diluted  with  turpentine 
without  disadvantage,  and  after  a few  applieations 
the  surface  will  take  on  a dull,  and  not  displeasing, 
polish.  The  table-tops  are  easily  cleaned  by  washing 
with  water  or  suds  after  a course  of  work  is  completed, 
and  the  application  of  another  coat  of  oil  puts  them 
in  excellent  order  for  another  eourse  of  work.  Strong 
acids  or  alkalies  when 
spilled,  if  soon  wiped  off, 
have  scarcely  a percepti- 
ble effect. 

The  writer  used  this 
method  on  some  old 
laboratory  tables  which 
had  been  finished  in  the 
usual  way,  the  wood 
having  been  filled,  oiled 
and  varnished.  After 
scraping  off  the  varnish 
down  to  the  wood,  the 
solutions  were  applied,  and  the  result  was  very  satis- 
factory. 

My  next  bit  of  home-made  apparatus  is  known 
among  my  friends  as  my  ‘‘family  four-poster.”  A 
glance  at  Fig.  5 will  show  at  once  its  very  simple 
nature.  It  consists  of  four  stout  posts  of  wood  about 
inches  square  and  perhaps  43^  feet  long.  These 
form  legs  or  pillars  of  a table  about  S}/2  feet  by  3 feet 
top.  Below  the  top,  at  convenient  distances,  I have 
in  my  own  case  put  four  shelves  (three  only  shown  in 

22 


DARK-ROOM  WORK 


sketch).  The  four  legs  are  on  casters,  for  convenience 
of  moving.  I find  this  a most  convenient  thing  for 
holding  several  large  trays,  or  washing  dishes,  when 
enlarging.  And,  as  will  be  seen,  it  is  a great  saver  of 
space;  for  one  does  not  often  find  an  amateur’s  dark- 
room with  table  space  for,  say,  three  dishes  to  hold 
20  X 16  prints,  as  well  as  the  usual  developing  and 
fixing  baths.  A friend  who  saw  my  ‘‘four-poster” 
adopted  and  adapted  the  idea  for  his  own  cupboard 
dark-room,  and  employs  it  to  hold  nearly  everything 
he  uses,  except  what  goes  on  the  small  housemaid’s 
sink  and  small  shelf  over  the  sink.  The  contrivance 
is  useful  for  drying  purposes.  All  apparatus  is  removed 
and  a sheet  of  clean  blotting  paper  put  upon  each  of 
the  shelves,  and  on  the  paper  is  laid  the  plates  or 
prints  to  dry  where  they  are  reasonably  safe  from 
falling  dust.  When  I am  preparing  for  a trip  from  home 
all  the  shelves  are  cleaned,  and  then  I here  collect  all 
the  odds  and  ends  which  I think  I may  want  when 
away  from  home.  Other  uses  will  suggest  themselves 
to  other  workers  according  to  their  needs.  The  top 
of  this  table  should  be  prepared  or  protected  as  dealt 
with  in  the  preceding  paragraph. 

In  Fig.  6 is  shown  another  very  homely  bit  of  ap- 
paratus which  has  stood  under  my  sink  for  some  years, 
and  holds  dishes  and  trays  of  all  shapes,  sorts  and  sizes. 
The  apparatus  was  one  morning  quickly  knocked 
together,  using  a packing  case  which  had  just  come 
to  hand.  This  was  done  by  way  of  a trial,  with  the 
intention  of  making  something  more  tidy  and  elaborate. 
But  this  rough  box  has  so  well  filled  my  wants  that 
I am  content  to  let  well  enough  alone.  N.  B. — Porce- 

23 


DARK-ROOM  WORK 


lain  and  glass  dishes  should  not  be  stored  flat  down, 
one  inside  or  resting  on  the  other.  Experience  long 
ago  taught  me  that  this  was  the  most  breakable  way 
of  doing  things.  Under  my  sink  I fix  a shelf,  after 
the  manner  shown  in  Fig.  5.  On  this  shelf  stands  my 
fixing-bath  for  all  plates  of  10  x 12.  This  dish-holding 
rack  just  easily  goes  under  the  fixing-bath  shelf. 
Thus  no  room  is  wasted.  The  fixing-shelf  is  large 
enough  for  two  fixing-baths,  side  by  side.  It  is,  I 
think,  as  well  to  give  a 
plate  likely  to  be  of  more 
than  momentary  interest 
a second  bath.  The  plate 
remains  in  bath  No.  1 
until  all  milky  appearance 
is  gone,  and  then  goes 
into  bath  No.  2 for  about 
an  equal  length  of  time. 

Bath  No.  2 is  always  kept 
as  clean  as  possible;  and  at  fairly  frequent  intervals 
No.  1 is  emptied  out  and  the  contents  of  No.  2 put 
in  No.  1,  and  a new  lot  of  hypo  solution  put  into 
tray  No.  2. 

The  experimental  photographer  very  soon  finds  that 
he  wants  a lot  of  odd  size  carriers.  For  example,  he 
may  wish  to  cut  up  a half-plate  into  three  equal  pieces 
and  use  these  strips  in  a half-plate  camera.  He  soon 
finds  that  it  takes  too  much  time  and  money  to  be 
having  these  carriers  made.  Fortunately  it  is  a very 
easy  matter  to  make  quite  efficient  carriers  out  of 
stiff  card  for  all  small  sizes,  up  to  whole  plates,  and  of 
thin  wood  for  large  sizes.  For  example,  suppose  we 

24 


DARK-ROOM  WORK 


wish  to  make  a carrier  to  hold  a 2 x 3 plate  in  an 
ordinary  half-plate-size  holder.  First,  cut  a piece  of 
card  the  size  of  the  holder,  viz.,  4i^  x 63^.  Out  of 
its  center  (found  by  drawing  diagonal  lines)  cut  out 
an  opening  just  taking  easily  the  2x3  plate.  Next 
cut  a second  piece  of  card,  ’j/^-inch  all  the  way  round 

less  the  first,  viz., 
434  X 6,  and  from  its 
center  cut  an  opening 
just  3^-inch  less  all 
the  way  round  than 
the  plate  it  is  to  sup- 
port. In  this  case  the 
plate  is  2 X 3 and  the 
opening  is,  therefore, 
1%  X 2^.  With  fish- 
glue  we  fix  these  two 
cards  together  so  that 
their  openings  are  concentric.  The  result  as  seen  from 
above  is  shown  in  Fig.  7,  A,  and  as  seen  from  below  is 
shown  in  Fig.  7,  C,  while  a section  is  shown  in  Fig.  7,  B. 
In  the  diagrams  the  reader  will  rightly  surmise  that 
for  clearness’  sake  we  have  drawn  the  thickness  of 
the  card  out  of  proportion.  Naturally,  we  shall  select 
card  of  suitable  thickness  to  agree  with  the  rebate 
of  the  plate-holder  in  which  it  is  to  be  used,  so  that 
the  slide  will  close  easily. 


Fig.  7. 


25 


Chapter  IV 


WATER  SUPPLY;  TAP  FITTINGS; 
TUBES  AND  RODS 

A GOOD  supply  of  water  is  essential  in  the  dark- 
room. There  should  be  two  taps  over  the  sink, 
and  one  of  them  should  be  sufBciently  high 
to  allow  of  filling  the  largest  bottles  under  it.  The 
water,  when  running  into  the  sink,  may  cause  splash- 
ing; to  prevent  this,  a short  length  of  rubber  piping 
may  be  slipped  over  the  end  of  the  tap,  or  a piece  of 
thin  cloth  a couple  of  feet  long  and  a few  inches  wide 
may  be  thoroughly  wetted  and  then  wound  tightly 
round  the  tap  so  that  the  projecting  cloth  forms  a 
tunnel  through  which  the  water  will  fall.  This  cloth 
may  cling  to  the  tap  if  tightly  wound,  but  it  is  safer 
to  hold  it  in  position  by  slipping  a strong  rubber  band 
over  it,  or  using  a piece  of  string,  to  ensure  its  not 
slipping  from  the  metal  pipe.  This  cloth  will  tend  to 
make  the  water  fall  in  a soft  even  column  instead  of 
a splashing  stream.  Filters  which  scarcely  affect  the 
flow  of  water  may  be  purchased  at  a nominal  price. 
The  filter  itself  is  a piece  of  fine  wire  gauze  in  a brass 
socket  which  attaches  to  the  tap  by  means  of  a rubber 
washer;  and  it  not  only  checks  splashing  but  also 
arrests  any  solid  particles  in  the  water.  The  second 
tap  should  be  fitted  with  a fine  rose  jet.  These  are  to 

26 


DARK-ROOM  WORK 


be  bought  mounted  on  a swivel  tap  by  which  the  rose 
may  be  swung  against  the  wall  when  not  in  use.  When 
pushed  against  the  wall  the  water  is  automatically 
turned  off;  when  drawn  forward  over  the  sink  it  gives 
a fine  spray  which  will  evenly  rinse  a plate  without  at 
all  damaging  the  film. 

The  tap  fittings  needed,  roughly,  are  three.  First, 
a short  piece  of  rubber  tubing  which  easily  can  be 
slipped  over  the  nozzle  of  the  tap.  In  the  other  end 


of  the  first  piece  of 


7\  tubing  is  a short  bit 


A 


VL 


-1/  of  stout  glass  tube. 
This  is  filled  with  bits 
of  charcoal,  and  over 
its  end  three  thick- 
nesses of  clean  fine 
flannel  are  fixed.  This 
is  a handy  filter  for 
use  when  I want  water 
free  from  any  organic 
impurity  or  suspended 


(n 


c 


Fig.  8. 


matter,  as  in  making  or  washing  color  screens.  In  a simi- 
lar way,  to  my  second  bit  of  tube  is  fixed  a rose  or  spray. 


which  I had  bought  of  a hardware  dealer  for  ten  cents. 


This  is  of  brass,  and  in  shape  is  but  a small  edition  of 
the  rose  or  sprinkling  end  of  a greenhouse  watering-can. 
My  third  bit  of  tube  is  longer,  long  enough  to  reach 
from  the  tap  to  the  bottom  of  the  sink,  or  nearly  so. 
Into  the  free  end  I can  slip  various  shaped  pieces  of 
glass  tubing  according  to  my  needs.  One  of  these  I 
may  as  well  now  describe,  as  it  is  the  one  by  far  the 
most  often  used.  This  I call  my  current-producer. 


27 


DARK-ROOM  WORK 


A piece  of  soft  glass  tube  is  selected,  of  such  a size  as 
to  hold  firmly  when  slipped  inside  the  rubber  tubing. 
This  is  softened  in  a batwing  gas  flame  and  gently 
drawn  to  such  a shape  as  shown  in  Fig.  8,  A.  Next 
applying  the  flame  edgeways,  we  again  soften  locally 
and  get  a bend  such  as  is  shown  in  Fig.  8,  B.  When 
cool  a file  scratch  at  C enables  us  to  part  the  tube  at 
this  point.  The  ori- 
fice at  C should  be 
1-6  or  1-8  inch  in- 
ternal diameter.  If 
slightly  larger  it  can 
easily  be  contracted 
by  gently  heating 
again  at  the  edge 
of  the  flame.  This 
also  softens  off  the  rough  edges.  This  simple  bit  of 
apparatus  is  very  useful  when  one  wants  to  quickly 
wash  a few  prints.  Fig.  9 shows  how  it  is  used  in 
conjunction  with  a shallow  tray.  The  outlet  of  the 
tube  is  arranged  so  that  a fine  stream  rushes  along 
the  side  from  A toward  B,  thence  out  to  C and  out 
at  D,  as  indicated  by  the  curved  arrow. 

An  ordinary  gummed  label  soon  comes  off  in  the 
frequently  damp  atmosphere  of  the  dark-room.  Sized 
and  varnished  it  will  last  as  long  as  the  bottle,  prac- 
tically. The  writer  has  had  such  labels  in  use  for 
years  in  the  acid-laden  atmosphere  of  a chemical 
laboratory  without  their  showing  signs  of  leaving 
their  supports.  Use  a thin  paper,  make  the  bottle 
dry  and  rub  the  gummed  and  moistened  label  down. 
Then  apply  a coating  of  size  (1  part  of  glue  in  10  parts 

28 


DARK-ROOM  WORK 


of  hot  water),  and,  when  quite  dry,  varnish  with  an 
“oak”  or  “church”  varnish,  i.  e.,  a varnish  containing 
linseed  oil.  Spirituous  varnishes  (as  used  for  nega- 
tives) do  not  last  so  well. 

For  attaching  the  labels  a mixture  of  glue  and  gum 
is  better  than  gum  alone.  Here  is  a good  formula  which 
is  easily  made  up:  Soak  1 part  of  the  best  glue  in 
water  until  thoroughly  swollen,  add  a little  sugar 
candy,  1 part  of  gum-arabic  and  6 parts  of  water. 

Boil  with  constant  stirring  over  a spirit 
lamp  until  the  whole  gets  thin.  The 
moisture  does  not  keep;  coat  sheets  of 
paper  with  it,  let  dry  and  cut  up  into 
convenient  sizes. 

To  prevent  written  labels  getting 
“smudged,”  use  water-proof  ink  when 
writing  on  the  paper.  Let  this  dry  very 

n thoroughly.  Then  coat  your  label  with  the 
following  varnish : Cut  up  into  fine  shreds 
an  old  celluloid  negative  film,  from  which 
you  have  previously  removed  all  traces  of 

the  gelatine  coating.  Put  these  shreds  in  a 

Fig.  10.  sniall  bottle.  Half-fill  with  amyl  acetate 
and  then  add  wood  alcohol  or  methylated  spirit. 
The  celluloid  will  become  dissolved.  Then  inside  the 
cork  of  your  bottle  fix  a trimmed  stiff  feather,  as  in  Fig. 
10.  This  forms  a.  convenient  brush  with  which  to 
coat  the  labels.  Two  or  three  coatings  should  be  given. 

A few  odds  and  ends  which  any  handy  person  can 
make  for  himself  may  now  be  described.  All  we  need 
are  as  follows:  a gas  (or  spirit  lamp)  flame,  a small 
three-cornered  file  which  need  not  cost  more  than  a 


29 


DARK-ROOM  WORK 


few  cents,  and  some  pieces  of  glass  tubing  and  rods 
(obtainable  at  any  chemical  apparatus  store).  First 
learn  to  cut  a tube.  Lightly  and  sharply  draw  one 
edge  of  the  file  across  a bit  of  tube.  You  may  see  that 
you  have  made  a tiny  scratch.  Now  seize  the  tube 
with  one  hand  on  each  side  of  this  crack  and  pull, 
rather  than  bend  it  apart.  One  or  two  trials  will 
quickly  show  the  way.  Next  bear  in  mind  to  slowly 
heat  glass  and  slowly  cool  it.  Do  not  thrust  the  tube 
straight  into  the  flame,  but  first  warm  it  a little  by 
holding  it  a 
few  inches 
above  the 
flame. 

Stirring 
rods  are  gen- 
erally made 
from  solid 
rod,  cut,  and 
the  sharp 
edges  round- 
ed  off  by 

heating  in  the  flame.  But  I prefer  a bit  of  small  tube 
with  each  end  closed  by  drawing  out  in  the  flame.  A 
tube  is  far  less  likely  to  smash  a delicate  glass  vessel 
than  is  a solid  rod  if  one  lets  it  slip.  One  end  of  a 
closed  tube  is  shown  in  Fig.  11,  A. 

Knob-ended  rods,  however,  are  very  useful  at  times. 
If  you  heat  the  end  of  a rod  in  the  flame  until  it  is 
quite  soft  and  then  press  it  down  upon  a bit  of  metal, 
such  as  a knife-blade,  or  face  of  a hammer,  you  get 
an  end  something  like  that  shown  in  Fig.  11,  B.  Sup- 

30 


DARK-ROOM  WORK 


pose  you  find  a slight  fog  veil  on  a negative.  Take  an 
ordinary  cylinder-shaped  graduate.  Throw  into  it  a 
crystal  of  potassium  ferricyanide,  add  a teaspoonful 
of  water,  give  the  glass  a swish  and  pour  off  the  water. 
Then  with  your  knob-ended  rod  crush  and  grind  the 
red  crystal  to  powder.  The  wet  bottom  of  the  grad- 
uate prevents  the  particles  flying  about.  Then  add  an 
ounce  or  two  of  hypo  from  your  hypo  jug,  and  you 
have  a fog  reducer  at  hand  in  a moment.  From  the 
sketch  it  will  be  seen  that  the  knob  is  more  conven- 
iently flat,  rather  than  round.  This  shape  is  much 
better  for  crushing  purposes. 

A spade-shaped  rod  end  is  very  useful  for  loosening 
the  contents  of  bottles,  which  have  become  more  or 
less  obstinate,  such  as  often  happens  with  small  crystals 
of  soda  sulphite,  alum,  borax,  etc.  This  shape  is 
shown  in  Fig.  11,  C.  Soften  the  end  of  the  rod  and 
then,  when  quite  pliant,  seize  it  suddenly  with  a pair 
of  flat-ended  pliers,  or  seize  between  two  flat-irons. 

A hook-shaped  end  is  also  useful.  See  Fig.  11,  B. 
First  heat  and  slightly  draw  out  the  rod,  then  curve 
and  cut  when  cold.  We  now  require  a short  length  of 
tube,  wide  enough  to  admit  the  hook  and  a trifle  to 
spare  over  that.  A bit  of  absorbent  cotton  is  shaped 
something  like  a small  sausage.  It  is  then  caught  in 
the  middle  by  the  glass  hook  and  pulled  up  into  the 
mouth  of  the  tube,  as  in  Fig.  11,  D.  This  forms  a 
very  useful  brush  when  it  is  needed  to  apply  delicate 
solutions  to  paper,  as,  for  instance,  local  toning  in 
platinum  or  velox  printing.  It  is  also  useful  for  local 
applications  of  acids  and,  being  entirely  of  glass,  i.  e., 
no  metal  parts,  is  not  affected  by  the  usual  acids. 

31 


Chapter  V 


FILTERING  SOLUTIONS;  FILTER 
PAPERS  AND  STAND 

ORDINARY  solutions,  like  developers,  fixing 
and  toning  baths,  ought  to  be  so  made  up 
and  with  chemicals  of  such  purity  that  no 
filtering  is  necessary,  but  when  one  gets  a little  off 
the  beaten  track,  then  filtering  often  becomes 
necessary.  Filter  papers  are  of  various  qualities 
— Rhenish,  French  and  English.  French  and  English 
are  much  coarser  papers  than  Rhenish.  The  ideal 
paper  is  that  which  is  strong  enough  to  support 
large  volumes  of  liquid,  without  holes  through  which 
suspended  water  can  pass,  and  permitting  the  liquid 
itself  to  pass  rapidly.  One  of  the  best  papers  for  a 
photographer’s  dark-room  is  Schleicher  & Schiill’s 
No.  597,  Rhenish,  which  costs,  per  100  5-inch  papers, 
about  thirty  cents.  The  funnel  makes  a lot  of  dif- 
ference to  the  filtering.  A ribbed  funnel  is  best,  and 
ribs  which  wander  spirally  around  the  funnel  better 
than  those  which  are  vertical.  The  deeper  the  ribs 
the  quicker  the  filtration.  There  is  a funnel  sold — 
Hehner  & Richmond’s — with  specially  deep  ribs. 
Small  funnels  ought  to  have  a fine  stem.  Such  filter 
quicker.  For  large  funnels,  diameter  of  stem  does 
not  matter  much,  although  width  is  preferable. 

32 


DARK-ROOM  WORK 


Don’t  filter  if  you  can  do  anything  else.  It  is  better 
to  let  any  deposit  settle  (if  it  will)  and  pour  off  the 
clear  liquid  above  it.  You  should  never  filter  solu- 
tions containing  pyro,  hydroquinone  or  other  de- 
velopers which  oxidize  readily,  because  filtration 
exposes  the  solution  so  freely  to  the  air.  If  it  is  neces- 
sary to  filter  it  should  be  done  before  the  pyro,  etc., 
is  added. 

Do  not  filter  when  decanting  will  do  as  well.  Or 
perhaps  you  can  decant  three-fourths  or  so  of  a mix- 
ture which  has  been  set  aside  in  a bottle  for  a few  hours, 
and  need  only  filter  the  last  and  bottom  fourth  part. 
In  any  case,  let  the  tube  of  the  funnel  just  touch  the 
inside  of  the  bottle.  This  will  hasten  matters  a little, 
and  also  it  is  better  for  the  fluid  to  run  down  the  in- 
side of  the  bottle  in  a fine  stream  than  go  down  by 
splashing  drops. 

The  usual  way  of  folding  and  placing  a filter  paper 
in  a funnel  is  that  best  calculated  to  try  the  patience 

of  the  user. 
One-half  of  the 
funnel  is 
covered  by  one 
thickness  of 
paper,  the  other 
half  by  three 
thicknesses.  While  exercising  patience  on  this  account 
some  time  ago,  I filled  up  time  by  trying  various  fold- 
ings, and  so  hit  on  one  which  gives  only  one  thickness 
of  paper  all  the  way  round.  As  this  does  not  seem 
generally  known,  though  doubtless  it  has  been  dis- 
covered by  other  impatient  people,  I give  it  here. 

33 


DARK-ROOM  WORK 


Fig.  13. 


See  Fig.  12.  First  bring  the  point  of  A of  the  paper 
over  to  its  opposite  C,  and  make  the  diagonal  crease 
B D.  Open  out  the  paper  again.  Now  bring  the  point 
B over  to  D and  make  the  crease  A C.  Open  out 
again.  Turn  the  paper 
over  and  make  the  crease 
M N,  about  midway  be- 
tween B C and  A D. 

This  last  crease  is,  of 
course,  the  opposite  way 
to  the  first  two  creases. 

Turn  over  again  and 
bring  the  folds  M and 
N toward  each  other, 
obtaining  a result  shown 
in  Fig.  13.  This  now  fills  any  angle  of  funnel  and  has 
but  one  thickness  of  paper  between  the  contained 
liquid  and  the  walls  of  the  funnel. 

A filter  stand  is  a handy  contrivance.  Take  a block 
of  wood,  say  6 inches  square  and  an  inch  thick. 
Toward  one  corner  bore  a 
hole  exactly  to  fit  a 12-  or 
15-inch  length  of  broomstick. 

See  Fig.  14.  In  the  upper 
half  of  the  broomstick  drive 
half-way  home  three  or  four 
brass-head  nails,  at  a distance 
of  about  \}/2  inches  apart. 

Take  a stout  piece  of  copper 
wire.  At  one  end  make  a loop 
large  enough  to  hold  the  fun- 
nel to  be  used.  At  the  other  Fig.  14. 


34 


DARK-ROOM  WORK 


end  make  another  loop  a little  larger  than  the  broom- 
stick, i.  e.,  just  large  enough  to  pass  the  heads  of  the 
nails,  when  the  loop  is  horizontal,  but  not  in  any  other 
position.  A glance  at  the  figure  will  show  that  we  can 
readily  adjust  the  height  of  the  holder  to  suit  any 
bottle  or  graduate. 


35 


Chapter  VI 


CORKS  AND  BOTTLES 

CORKS  that  are  kept  dry  are  apt  to  get  hard  and 
lose  some  of  their  eleetricity.  This  may,  to 
a great  extent,  be  restored  by  soaking  in  warm 
water.  But  if  one  is  in  a hurry,  just  wrap  up  the  cork 
in  a bit  of  clean  paper  and  put  it  under  the  foot  and 
roll  it  about.  At  first  only  the  most  gentle  pressure 
must  be  used  or  the  cork  will  break.  Corks  soaked 
in  hot  melted  paraffin  wax  are  rendered  less  porous 
and  so  more  nearly  air-tight.  Corks  for  bottles  con- 
taining volatile  fluids  such  as  alcohol,  ether,  etc., 
should  be  coated  with  sealing-wax.  Put  the  cork  in 
the  bottle,  then  warm  a bit  of  good  wax  and  rub  on 
the  cork.  Now  take  an  old  knife,  make  it  warm  enough 
to  melt  the  wax,  and  with  it  spread  the  wax  all  around 
that  part  of  the  cork  which  is  now  outside  the  bottle. 
As  sealing-wax  is  soluble  in  various  fluids,  alcohol 
for  instance,  care  must  be  taken  to  keep  the  fluid 
from  touching  the  cork.  Any  vapors  of  these  fluids 
which  may,  however,  find  their  way  through  the  pores 
of  the  cork,  do  not  seem  to  have  any  effect  on  the  wax. 

Developer  bottles  with  corks  that  are  in  frequent 
use  are  apt  to  jump  out  of  one’s  fingers  (the  corks, 
not  the  bottles)  and  then  roll  to  the  most  inaccessible 
part  of  the  dark-room  floor.  It  is  easy  to  prevent  this. 

36 


DARK-ROOM  WORK 


See  Fig.  15.  Borrow  a crochet  hook.  Thrust  this 
through  the  upper  part  of  the  cork,  as  in  15  A,  then 
hitch  over  the  hook  a bit  of  string,  thin  string,  pull 
back  the  hook  and  the  string  with  it,  and  tie  the 
string  in  a loose  loop.  The  other  end  of  your  string 
is  tied  around  the  neck  of  the  bottle,  and  the  lengths 
are  so  adjusted  that  when  the  cork  is  out  of  the  bottle 
and  not  in  your  fingers  it  is  hanging  to  the  bottle,  and 
yet  not  touching  the  shelf  on  which  the  bottle  may  be 

standing.  This  will  be  ex- 
plained by  a moment’s  glance 
at  15  B. 

This  brings  us  to  ask 
whether  stoppers  are  better 
than  corks  for  the  photogra- 
pher’s solutions.  In  most 
cases  they  are  not;  in  many, 
they  are  not  so  suitable  as 
corks  (e.  g.,  for  all  alkali 
solutions),  for  they  are  liable 
to  stick.  The  only  instances 
where  a stoppered  bottle  is 
really  necessary  are  for  solu- 
tions of  gold  chloride  and 
potassium  chloro-platinite  (which  are  decomposed  and 
reduced  to  the  metallic  state  by  contact  with 
organic  matter  like  cork),  and  for  strong  acids 
such  as  hydrochloric  and  sulphuric,  which  speedily 
destroy  cork  or  rubber.  For  all  other  solutions  corks 
are  just  as  good  as  stoppers,  bearing  in  mind  that  the 
cork  is  porous  and  absorbs  the  solution  which  it 
isolates  from  the  air;  the  photographer  must  not  there- 

37 


DARK-ROOM  WORK 


fore  indiscriminately  transfer  corks  from  one  bottle 
to  another  without  an  hour  or  so  soaking  in  clean 
water. 

It  might  be  thought  that  nothing  could  be  said  on 
such  an  every-day  subject  as  bottles,  but  there  are  a 
few  points  which  conduce  to  comfort  in  one’s  dark- 
room. The  type  of  bottle  selected  should  be  one  with 
a thin  lip  projecting  a good  way  round  the  rim — not 
one  with  a thick,  square  lip.  The  former  allows  the 
liquid  to  be  poured  out  without  wasting  a drop;  with 
the  latter  it  is  impossible  to  deliver  small  quantities 
without  some  of  the  solution  dribbling  down  the  side 
and  into  the  coat  sleeve  of  the  victim. 

The  bottles  for  one’s  set  of  solutions,  e.  g.,  pyro, 
bromide  and  alkali,  may  very  fitly  be  selected  of  dis- 
tinctly different  size  and  shape,  so  that  they  cannot 
be  mistaken  in  the  rosy  gloom  of  the  dark-room.  As 
suggested  some  time  ago,  the  bottle  proposed  for 
poisons  and  in  shape  like  a fashion-plate  young  lady, 
i.  e.,  nipped  in  at  the  middle,  might  be  adopted  for 
pyro  were  it  not  to  be  feared  that  by  a natural  associa- 
tion of  ideas  the  photographer  might  pass  from  clasp- 
ing of  the  waist  to  pressing  to  the  lips — with  disastrous 
results. 

Two  hints  ought  to  be  so  borne  in  mind  that  the 
practice  of  them  becomes  habitual.  Always  keep  the 
label  uppermost  when  pouring  from  a bottle,  so  that 
if  any  liquid  trickles  down  the  side  the  label  misses  it. 
Result — your  labels  keep  clean  and  legible  for  much 
longer.  Secondly,  if  you  want  to  deliver  drops  (or 
a very  small  quantity)  of  liquid,  just  moisten  the  lip 
of  the  bottle  with  the  finger.  The  fiuid  then  trickles 

38 


DARK-ROOM  WORK 


out  without  having  to  overcome  the  resistance  of  a 
dry  patch. 

I could  easily  fill  pages  with  directions  for  cleaning 
bottles  which  have  contained  this  or  that  chemical. 
But  it  doesn’t  pay  to  spend  time  over  such  business. 
If  water  does  not  clean  the  bottle  right  away  try 
shaking  a little  hydrochloric  acid  in  it;  if  this  is  of  no 
use,  shake  up  (still  with  the  hydrochloric  acid)  with 
shot,  or  small  coal,  or  coarse  sand  or  something  which 
will  scrape  the  impurity  of  the  side.  If  this  fails,  cast 
the  bottle  aside  as  useless. 

Commercial  hydrochloric  acid  is  a solvent  of  many 
precipitates,  sediments,  deposits,  which  are  not  re- 
moved by  water,  and  it  is  pretty  safe  to  say  that  what 
is  not  removed  by  it  must  be  rubbed  off  by  friction. 
Keep  the  spirit  mixed  with  an  equal  volume  of  water, 
and  see  that  you  do  not  splash  any  of  it  (neat  or 
diluted)  on  clothes  or  upholstery,  for  it  leaves  a rotten 
and  stained  patch  as  a memento 
of  its  visit.  Dishes,  measures,  etc., 
if  rinsed  out  once  or  twice  with 
this  liquid  are  easily  made  quite 
clean,  as  a general  rule. 

If  the  acid  will  not  remove  any 
stain,  brisk  rubbing  with  a tuft  of 
any  kind  of  paper  will  almost  al- 
ways do  so.  I know  of  no  better 
way  of  cleaning  right  into  the  cor- 
ners of  bottles  and  dishes  than  this. 

If  you  wish  to  have  a ten  per  cent 
solution  of  bromide,  it  is  convenient 
to^have  it  in  a dropping  bottle.  A 
39 


DARK-ROOM  WORK 


dropping  bottle  can,  of  course,  be  made  by  cutting 
a couple  of  nicks  down  opposite  sides  of  the  cork,  but 
the  drops  are  very  apt  to  trickle  down  the  sides  of  the 
bottle,  and  make  both  it  and  the  shelf  it  stands  on 
unsightly.  Take  a bit  of  rather  narrow  glass  tube, 
soften  it  in  the  flame  and  gently  bend  it  and  then  cut 
to  suitable  length  and  insert  into  the  cork  of  your 
bottle,  taking  care  that  it  goes  just  a trifle  below  the 
inside  surface  of  the  cork.  Fig.  16  will  make  this 
quite  clear.  By  suitably  selecting  the  size  of  the  glass 
tube  you  will  And  that  you  can  deliver  about  five 
separate  drops,  parting  with  each  with  just  the  sus- 
picion of  a slight  shake  of  the  hand,  without  inverting 
the  bottle  to  let  in  air.  That  is  to  say,  with  a one-in-ten 
solution  of  potass,  bromide  we  can  very  conveniently 
add  half  a grain  of  bromide  as  fast  as  we  can  say 
“one,  two,  three,  four,  five.” 


40 


Chapter  VII 


A TRAY  ROCKER;  PLATE  LIFTERS; 
WEIGHING  AND  MEASURING 

From  dropping  bottles  we  naturally  pass  to 
aids  to  development.  One  of  the  most  useful 
and  simplest  things  is  just  a strip  of  wood  to 
put  under  the  middle  of  the  dish  as  it  rests  on  the 
table,  so  that  with  one  finger  one  can  rock  a whole- 
plate  dish.  For  quarter  and  half-plate  an  octagonal 
cedar-wood  lead  pencil  is  just  the  right  size  and  length. 
For  whole-plate,  up  to  10  x 12,  dishes  we  want  a round 

O piece  about 

twelve  inches 
long  and  say 
%-inch  in 
diameter. 
With  a plane 
we  remove  a 
little  of  this, 
so  as  to  make  it  rest  firmly  on  the  table  and  not  roll 
about.  To  make  this  quite  clear  I give  in  Fig.  17  a 
section  of  the  rod  of  wood,  and  below  we  see  this 
rod  resting  with  its  flat  side  on  the  table  and  a de- 
veloping dish  resting  on  the  rod.  One  need  hardly 
say  that  the  dish  must  not  be  allowed  to  stand  with 
all  the  developer  at  one  end  and  part  of  the  plate 

41 


Fig.  17. 


DARK-ROOM  WORK 


uncovered,  as  shown  in  the  figure.  A few  handy  plate- 
lifters  should  find  a place  on  every  dark-room  sink  shelf. 
We  often  enough  want  to  be  attending  to  two  or  three 
plates  in  as  many  different  solutions.  One  or  two 
plate-lifters  enable  us  to  lift  the  plate  up  and  see  how 
matters  are  going  without  contaminating  one’s  fingers 
with  the  solution.  In  Fig.  18  two  equally  convenient 
forms  are  shown.  That  marked  A is  easily  made  from 
the  bone  handle  of  a worn-out  tooth-brush.  All  one 
needs  is  a file  and  a little  patience.  Do  not  make  the 
likely  mistake  of  making  the  finger-nail-like  end  too 
sharp  and  thin  at  its  edges,  or  you  will  find  your  plate- 
lifter  become  a plate-scratcher. 

All  sharp  edges  should  be  well 
rounded  off  with  glass  paper, 
or  by  rubbing  on  a stone.  The 
above  caution,  of  course,  equally 
applies  to  form  B,  Fig.  18.  In 
this  case  our  plate-lifter  is  of 
somewhat  larger  size,  and  made 
out  of  a bit  of  broken  vulcanite  tray.  A piece  was 
roughly  shaped  with  a saw,  then  softened  by  immers- 
ing in  hot  water  and  bent  to  shape.  When  cold  it  was 
finished  up  with  a file  and  glasspaper. 

The  handiest  measures  for  the  dark-room  are  the 
tumbler-shaped  ones.  They  are  less  liable  to  break 
than  those  running  down  to  a point  and  standing  on 
a flat  glass  foot.  But  they  are  of  no  use  for  measuring 
very  small  quantities  of  solution,  and  so  one  or  two 
small-sized  conical  ones  should  be  kept  at  hand, 
preferably  the  sort  fitted  with  hard  rubber  bases. 
Dishes,  at  any  rate  in  small  sizes,  are  of  poreclain, 

42 


Fig.  18. 


DARK-ROOM  WORK 


glass,  papier-mache,  compressed  fiber,  hard  rubber 
and  tin.  Porcelain  is  the  most  desirable  despite  its 
cost;  it  has  the  advantage  of  showing  any  dirt  or 
stain,  and  thus  conducing  to  cleanliness.  Glass  trays 
are,  if  anything,  less  liable  to  breakage  than  porcelain. 
Composition  and  metal  trays  are  light  and  practically 
unbreakable;  when  they  begin  to  look  worn,  or  rust 
and  leak,  they  should  be  thoroughly  scrubbed  in  soap 
and  hot  water,  and  then  coated  inside  and  out  with 
varnish  or  Probus. 

There  is  such  a thing  as  needless  accuracy  in 
weighing  and  measuring.  It  is  no  good  weighing 
chemicals  more  accurately  than  the  solutions  contain- 
ing them  can  be  measured.  From  tests  which  I got 
some  careful  photographic  friends  to  do  in  conjunction 
with  personal  tests  some  time  ago  I found  that  in 
broad  daylight  their  measurements  of  solutions  (1  or 
^ ounces)  varied  about  1 per  cent  (1  in  100)  on  either 
side  of  the  truth,  i.  e.,  total  error  of  2 per  cent.  Hence 
weights  can  be  safely  just  as  inaccurate — but  not  more 
so.  This  means  that  an  “ounce”  of  say,  potassium 
bromide,  may  be  4.37  (1-100  of  an  ounce)  more  or 
less  than  an  ounce  without  “cutting  any  figure.” 
In  other  words,  it  may  be  441.8  or  433.1  grains.  This 
means  that  the  trouble  of  finally  adjusting  the  weight 
to  one-half  a grain  is  simply  wasted.  When  small 
quantities,  20  grains  and  less,  are  being  weighed  the 
greatest  accuracy  must  be  observed. 

Every  dark-room  ought  to  have  two  balances — 
one  for  weighing  small  quantities  up  to,  say,  a quarter 
of  an  ounce,  and  another  from  this  latter  quantity 
up  to  a pound  or  so.  The  first  is  for  chemicals  required 

43 


DARK-ROOM  WORK 


in  small  amounts,  but  with  approximate  exactness; 
the  second  for  substances  such  as  hypo  or  potassium 
oxalate,  which  need  not  be  weighed  with  special 
accuracy.  For  the  former,  the  ordinary  beam  balance 
of  the  dealers,  preferably  with  glass  pans,  is  the  best, 
for  the  latter  a spring  balance  with  a good-sized  pan, 
6 inches  or  more  in  diameter  and  detachable  from 
its  setting.  To  those  who  care  to  go  to  the  expense, 
the  most  convenient  plan  of  any  is  to  combine  these 
two  scales  in  one  and  to  use  a Beranger  balance.  An 
instrument  of  this  pattern  carrying  two  pounds  is 
delicate  enough  for  the  smaller  quantities  a photog- 
rapher requires,  but  it  is  expensive.  When  very  small 
quantities  of  chemicals  have  to  be  weighed  out  it  is 
best  to  make  instead  a stock  solution  (10  per  cent  or 
1 per  cent),  and  to  measure  of  this  the  quantity  re- 
quired to  give  the  weight  of  salt.  Thus,  instead  of 
weighing  2 grains  of  sodium  sulphite  (for  a toning 
bath)  I would  dissolve  44  grains  in  10  ounces  of  water 
(i.  e.,  make  a 1 per  cent  solution)  and  use  200  minims. 

It  is  of  the  utmost  importance  to  keep  the  pans  of 
the  balance  scrupulously  clean.  That  is  why  glass  is 
best;  practically  no  chemical  attacks  it.  But  there 
is  no  need  to  place  the  salt  on  the  bare  pan.  In  fact, 
this  should  never  be  done.  Cut  out  circular  discs 
of  paper  and  keep  a stock  handy,  placing  one  on  each 
pan.  Or  a better  way  is  to  get  a little  aluminum  bowl 
or  dish  which  will  stand  on  the  pan  and  to  cut  a counter- 
poise for  it  out  of  sheet  lead.  It  is  quite  easy  to  clean 
a separate  vessel,  but  not  so  in  the  case  of  the  pans. 

When  liquids  have  to  be  weighed  a glass  vessel  must 
be  counterpoised.  The  best  for  the  purpose  is  the 

44 


DARK-ROOM  WORK 


beaker  (of  the  analytical  chemist)  of  the  low  and  wide 
type.  It  is  very  light,  stands  steadily  on  the  pan  and 
pours  cleanly;  but  it  must  be  most  carefully  handled, 
for  it  is  very  thin  and  broken  at  once  if  squeezed  or 
set  down  hurriedly  on  a hard  place. 

Generally  it  is  most  convenient  to  measure  liquids 
rather  than  weigh  them. 

Measuring  solutions  requires  separate  treatment. 


If  you  look  closely  at  some 
water  standing  in  a measure 
you  will  see  that  the  sur- 


Ct  face  is  convex  on  the  under 
side.  Measures  are  gradu- 
ated— or  are  supposed  to 
be  graduated — so  that  they 
hold  the  given  amount  when 
the  lowest  point  of  this 
curve  coincides  with  the 
line  of  the  graduation.  In 
measuring  volumes  of  liquid 
of  an  ounce  and  upwards 
this  is  a refinement  which 
can  be  entirely  ignored. 


Fig.  19. 


but  when  measuring  out  a few  minims  it  is  well  to 
bear  in  mind  that  a (Fig.  19)  is  the  correct  reading 
for  10  minims,  and  not  h. 

Remember,  also,  when  measuring  out  small  volumes 
such  as  these  (a  few  minims  only)  that  a large  propor- 
tion of  the  liquid  clings  to  the  sides  of  the  measure, 
and  unless  the  latter  is  rinsed  out  with  a little  water 
you  don’t  get  all  the  indicated  solution.  The  difference 
is  appreciable  in  measuring  out  bromide  solutions  into 

45 


DARK-ROOM  WORK 


small  lots  of  developer,  gold  into  toning  bath,  or 
platinum  chloro-platinite  into  a platinotype  sen- 
sitizing solution. 

A very  handy  fitment  for  measuring  small  volumes 
of  liquids  quickly  is  a glass  tube  drawn  out  to  a fine 
point  at  one  end  and  fitted  with  a rubber 
teat  or  bulb  at  the  other,  i.  e.,  a fountain 
pen  “filler.”  It  is  graduated  by  scratching 
with  a file  at  various  points,  which  are 
best  found  by  trial  and  error.  Stick  a scrap 
of  sharp  edging  at  the  point  where  you 
think  the  30-minim  mark  should  be,  and, 
pressing  the  bulb,  draw  up  some  water; 
expel  the  water  until  the  level  stands  at  the 
top  of  the  edging  and  then  discharge  the 
tube  into  a minim  measure,  or,  more  ac- 
curately, into  a little  dish  which  has  been 
balanced  on  a balance.  If  the  guess  is 
right  scratch  a mark  with  a file;  if  not, 
try  again.  A tube  of  this  kind  is  very 
easily  made  and  serves  to  measure  solu- 
tions, such  as  bromide,  very  rapidly  and 
accurately.  A good  plan  is  to  keep  it 
thrust  through  the  cork  of  the  bottle  in 
which  the  stock  solution  is  kept.  This  will  necessitate 
a goodly  number  of  graduated  tubes,  but  will  repay 
the  trouble.  (See  Fig.  20). 


30 

25 

20 


10 

5 


Fig.  20. 


4G 


Chapter  VIII 


MAKING  SOLUTIONS 


HERE  are  several  factors  which  contribute 


to  the  rapid  compounding  of  a solution — the 


quality  and  fineness  of  division  of  the  chemicals, 
the  temperature  of  the  water  and  the  way  the  two  are 
mixed.  By  looking  after  these  points  much  time  and 
labor  can  often  be  saved.  Let  us  consider  them  in 
the  above  order. 

Some  chemical  substances  are  very  soluble  in  water 
and  some  are  not.  It  is  their  nature  and  nothing  will 
alter  it.  But,  nevertheless,  there  are  various  devices 
which  the  photographer  can  practice  by  which  he 
can  get  over  some  diflficulties  nature  puts  in  his  way. 
Let  him  not  forget  that  the  remedies  are  also  nature’s. 
An  “anhydrous”  salt,  i.  e.,  one  deprived  of  water 
crystallization,  dissolves  much  more  quickly  than  the 
crystallized  substance.  Anhydrous  sodium  carbonate 
and  sodium  sulphite  (see  elsewhere)  are  two  of  the 
best  known  instances,  and  are  obtainable  commercially. 
Do  not  suppose  that  because  a salt  is  anhydrous,  it 
is  therefore  soluble.  The  fact  is  that  the  anhydrous 
salt  does  not  lower  the  temperature  of  the  water  in 
which  it  dissolves  as  does  the  crystallized  salt. 

A second  method  of  aiding  the  solution  of  a salt  is 
to  add  some  second  substance  which  has  no  effect 


47 


DARK-ROOM  WORK 


on  the  action  of  the  first.  A most  useful  example  is 
that  of  mercuric  chloride.  If  powdered  and  mixed 
with  an  equal  weight  of  ammonium  chloride  it  dissolves 
very  readily. 

A wedgewood  pestle  and  mortar  is  the  best  thing 
for  powdering  chemicals.  In  purchasing  one  see  that 
you  get  a pestle  with  a fairly  fiat  end.  A too  rounded 
end  is  less  efficient  for  the  purposes  of  the  photographer, 
who  does  not  want  exceptional  fineness,  and  is  apt 
to  throw  the  crystals  out  when  used  with  sudden  vigor. 
Make  a point  of  cleaning  the  mortar  directly  after  use. 

In  the  absence  of  a mortar  a piece  of  stout  brown 
paper  and  a wooden  roller  or  mallet  does  the  work 
almost  as  well. 

The  hotter  the  water  the  more  freely  salts  dissolve 
in  it,  as  a general  rule.  I divide  here  the  common 
photographic  chemicals  into  2 classes. 

I.  Chemicals  dissolving  much  more  quickly  if  hot 
water  is  used:  Oxalic  acid,  hydroquinone,  alum,  borax, 
lead  nitrate,  mercuric  chloride,  potassium  ferricyanide, 
potassium  ferrocyanide,  potassium  oxalate,  sodium 
sulphite,  sodium  thiosulphate  (hypo).  For  these  it 
is  worth  while  to  use  hot  water. 

II.  Chemicals  dissolving  very  quickly  in  cold  water: 
Ammonium  sulphocyanide,  ammonium  bromide,  citric 
acid,  potassium  bromide,  potassium  carbonate,  potas- 
sium cyanide,  potassium  bichromate,  potassium  hy- 
droxide (caustic  potash),  sodium  acetate,  sodium  car- 
bonate, sodium  hydroxide  (caustic  soda),  sodium 
chloride  (common  salt),  uranium  nitrate.  For  these 
it  is  of  no  advantage  to  use  hot  water. 

I must  add  that  some  salts  must  not  be  dissolved 


48 


DARK-ROOM  WORK 


in  hot  water  if  they  are  to  be  obtained  unaltered  in 
the  solution.  The  chief  of  these  are:  Potassium 
metabisulphite,  sodium  bicarbonate,  sodium  sulphanti- 
monate  (Schlippe’s  salt). 

To  get  hot  water  quickly  in  the  dark-room  I prefer 
a small  gas  or  alcohol  stove.  Petroleum  is  not  so  clean. 
A small  alcohol  stove  can  be  had  at  hardware  stores 
which  will  boil  a pint  of  water  in  five  or  six  minutes. 
It  is  one  of  the  most  handy  things  you  can  have  in 
a dark-room  or  mounting-room. 

The  every-day  method  of  dissolving  salts,  viz., 
putting  them  in  a bottle  and  shaking  till  all  have  dis- 
appeared, is  bad,  because  it  needs  constant  attention. 
The  concentrated  solution  collects  at  the  bottom  of 
the  liquid  and  protects  the  solid  from  the  action  of 
the  still  unsaturated  liquid  above.  Hence  the  neces- 
sity of  frequent  shaking.  The  proper  method  of  solu- 
tion is  to  suspend  the  solid  at  the  top  of  the  liquid, 
by  suspending  the  chemicals  from  the  top  of  the  con- 
tainer in  a porous  bag  which  hangs  in  the  water. 


49 


Chapter  IX 


FACTS  ABOUT  CHEMICALS 

The  chief  things  one  wants  to  know  about  the 
chemicals  used  in  photography  are  not  their 
formulae  or  atomic  weights,  but  their  practical 
qualities,  i.  e.,  their  solubility,  keeping  properties,  the 
differences  in  name  and  fact  between  commercial 
varieties,  and  such  facts  as  the  impurities  likely  to 
be  found  in  the  chemicals  we  buy  at  the  stores,  how 
far  these  impurities  are  harmful,  and  how  they  can  be 
minimized  or  removed. 

As  a rule,  chemicals  are  more  readily  soluble  in 
hot  than  in  cold  water,  so  that  if  more  than  the  quantity 
soluble  in  cold  water  is  dissolved  by  the  aid  of  heat, 
the  excess  of  the  salt  will  separate  when  the  solution 
is  cooled.  Such  a solution  is  said  to  be  "‘saturated”  in 
the  cold,  and  for  a given  temperature  contains  always 
a certain  definite  quantity  of  salt.  Generally  60° 
Fahr.  (15.5°  C.)  is  the  temperature  which  is  presumed 
when  talking  about  cold  saturated  solutions.  There 
are  two  ways  of  expressing  solubility.  We  can  say 
how  much  of  the  solid  is  contained  in  a given  volume 
of  saturated  solution  ; or  we  can  say  how  much  of  the 
solid  is  required  to  saturate  a given  volume  of  water; 
other  things  being  equal,  the  latter  is  always  rather 
more  than  the  former. 


50 


DARK-ROOM  WORK 


The  practical  thing  to  remember  about  solubility 
and  making  solutions  is,  that  if  left  to  themselves  at 
the  bottom  of  a bottle  most  chemicals  do  not  forthwith 
form  a saturated  solution.  This  point  is  gone  into  more 
fully  in  the  section  on  making  solutions.  Note  here 
that  as  chemicals  generally  dissolve  more  freely  in 
hot  water  than  in  cold,  the  straight  way  to  get  a 
saturated  solution  is  to  take  more  of  the  salt  than  is 
necessary  (see  figures  later),  dissolve  and  cool.  There 
should  be  a deposit  at  the  bottom  of  the  vessel  if  all 
is  well. 

Many  chemicals  do  not  keep  indefinitely.  Their 
failing  in  this  respect  is  mentioned  seriatim  below. 
As  a general  rule,  all  chemicals  should  be  kept  tightly 
stoppered  and  in  the  dark.  In  particular  are  developers 
(pyro,  etc.),  sulphites,  sulpho-cyanides,  ferrous  and 
ferric  salts  (the  former  oxidize  in  the  air,  some  of  the 
latter  reduce  on  exposure  to  light),  silver,  gold  and 
platinum  salts  (get  “reduced”  in  the  light).  Among 
others  which  spoil  by  absorbing  moisture  from  the 
air,  and  which  must,  therefore,  be  tightly  stoppered 
are  ammonium  and  potassium  sulpho-cyanides,  uran- 
ium nitrate  and  chloride,  calcium  chloride,  bleaching 
powder,  ferric  chloride  (iron  perchloride),  potassium 
carbonate,  caustic  potash,  potassium  cyanide,  caustic 
soda  and  sodium  sulphite. 

The  permanence  or  otherwise  of  a chemical  solution 
is  a matter  of  conditions — generally  whether  the  air 
gets  access  to  the  liquid  or  not.  Two  methods  of 
preserving  solutions  from  the  action  of  the  air  are 
worth  bearing  in  mind.  The  first  is  to  store  the  solu- 
tion in  a lot  of  small  bottles,  say  4-ounce  capacity, 

51 


DARK-ROOM  WORK 


each  filled  to  the  lip  and  well  corked.  The  second  is 
to  store  the  solution  in  a bottle  with  a cork  at  the 
bottom  such  as  is  described  above,  and  to  pour  a 
layer  of  “heavy”  paraflSn  oil  on  the  top  of  the  solution. 
The  oil,  although  designated  heavy,  is  lighter  than 
water,  has  no  action  on  any  ordinary  solution  and 
effectually  excludes  the  air. 

Developers  and  other  solutions  must  be  kept  fairly 
reasonably  around  60°  Fahr.,  i.  e.,  from  55°  to  65° 
Fahr.  To  do  this  in  sum- 
mer and  winter  is  not 
always  easy.  In  winter 
remember  that  it  is  not 
enough  that  the  de- 
veloper only  be  at  the 
right  temperature.  If  the 
room  be  nearly  down  to 
freezing,  the  developer 
will  be  chilled  the  mo- 
ment it  is  poured  into 
the  dish.  Where  it  is 
not  possible  to  keep  the  room  warmed  the  following 
simple  arrangement  is  easily  made.  A large  square 
tank  is  filled  with  water  at  65°  (or  other  tempera- 
ture) and  a metal  frame  fitted  in  the  top  so  that 
the  dish  can  be  immersed  to  nearly  the  level  of  the 
water  (see  Fig.  21).  Such  a large  volume  of  water 
does  not  alter  in  temperature  very  quickly,  and  a test 
every  now  and  then  with  a thermometer  keeps  matters 
right.  Those  who  do  not  want  to  go  to  this  trouble 
should  arrange  a shelf  over  their  dark-room  lamp  on 
which  they  can  place  developing  dishes  or  bottles. 

52 


Fig.  21. 


DARK-ROOM  WORK 


A little  adjustment  will  enable  them  to  get  just  the 
right  degree  of  warmth. 

In  summer  the  problem  of  cooling  developing  and 
toning  solutions  is  not  so  easily  solved.  Ice  is  generally 
at  hand  during  the  summer  months.  Where  it  can  be 
had  these  diffiulties  disappear.  One  way  of  getting 
a supply  of  cooled  water  is  to  wrap  up  a large  bottle 
of  the  water  to  be  cooled  in  rags  which  are  placed 
somewhere  in  a draught  and  kept  well  wetted.  The 
heat  absorbed  by  the  evaporation  of  the  water  is  sup- 
plied by  the  water  in  the  bottle,  which  thus  becomes 
cooler.  It  may  be  added, — though  this  is  getting  a 
little  outside  the  province  of  this  book, — that  the  less 
the  fingers  are  placed  in  the  baths  used  in  summer,  the 
better. 


53 


Chapter  X 


WASHING  PLATES  AND  PRINTS; 
DRYING 

There  is  a good  deal  of  misconception  about  the 
proper  amount  of  washing  required  for  plates 
and  papers.  The  word  “washing”  suggests  the 
drastic  methods  of  the  laundress,  and  indeed  some 
writers  seem  to  suggest  that  the  hypo  and  other  salts 
which  we  aim  to  remove  are  “knocked  off”  the  gelatine 
film  by  a stream  of  water  something  after  the  manner 
of  the  ash  from  a cigar.  As  a matter  of  fact,  the  re- 
moval of  hypo  from  a gelatine  depends  upon  a process 
of  diffusion,  not  abrasion,  the  facts  about  which  are, 
briefly,  as  follows:  Liquids  which  mix,  say  pure  water 
and  strong  hypo  solution,  do  so  even  though  the 
heavier  solution  be  at  the  bottom.  Thus  a layer  of 
strong  hypo  solution  carefully  lowered  by  a funnel 
to  the  bottom  of  some  water  standing  in  a tall  cylinder 
will,  in  course  of  time,  gradually  mix  as  completely  as 
though  the  whole  had  been  stirred  together.  The 
force  of  diffusion  overcomes  the  attraction  of  gravity. 
Had  the  strong  solution  been  introduced  at  the  top 
of  the  water,  gravity  and  diffusion  acting  together 
would  have  brought  about  this  uniform  mixture  much 
more  rapidly. 

Now  these  facts  give  the  key  to  the  common  sense 
54. 


DARK-ROOM  WORK 


of  washing  both  plates  and  prints.  The  gelatine  film, 
fresh  from  the  fixing  bath,  is  full  of  strong  hypo  solu- 
tion. If  left  at  the  bottom  of  a dish  of  water  the  hypo 
will  gradually  diffuse  out,  but  it  will  do  so  much  more 
rapidly  if  the  outgoing  solution  can  fall  away  from  the 
film,  because  the  rate  of  diffusion  is  greatest  when  the 
difference  in  strength  of  the  two  solutions  is  greatest. 
In  other  words,  we  want  to  intermittently  replace  the 
solution  next  the  plate  by  pure  water,  so  that  the  strong 
hypo  solution  in  the  film  may  have  the  greatest  in- 
ducement to  pass  out.  If  properly  conducted  this 
process  is  not  at  all  slow.  Experiments  by  Haddon  & 
Grundy  and  by  Gaedicke  have  shown  that  a series 
of  5-minute  soaks  rapidly  reduces  the  residual  hypo 
in  plates  or  paper  to  a negligible  minimum.  The 
number  of  soaks  need  not  be  more  than  five  or  six, 
which  means  that  half  an  hour’s  washing  practically 
does  everything  that  can  be  done. 

The  best  commercial  pattern  among  negative 
washers  is  a siphon  or  other  washer  which  allows  some 
space,  say  2 inches  below  the  plates,  and  a depth  of 
water  above  them  equal  to  the  height  of  the  plates. 
The  washer  should  fill  slowly  and  empty  as  rapidly  as 
possible  (in  a few  seconds)  so  that  the  ideal  conditions 
— quiescent  soak  and  complete  removal  of  soak- 
water — are  approximately  realized.  There  is  no  ad- 
vantage in  the  expensive  arrangements  for  squirting 
jets  of  water  over  the  negative.  With  constant  change, 
an  hour’s  wash  at  the  most  is  all  that  is  necessary. 

In  the  case  of  prints  the  surest  and  simplest  way  of 
ensuring  the  frequency  of  change  is  by  hand,  though 
it  is  tedious.  Remove  each  print  slowly  from  the 
fixing  bath.  Much  of  the  hypo  is  thus  dragged  out  of 

55 


DARK-ROOM  WORK 


the  paper  by  capillary  attraction  and  drains  away. 
Plunge  it  for  an  instant  into  clean  water  and  place  in 
dish  (A)  of  clean  water.  When  all  the  members  of  the 
batch  have  arrived  in  A,  remove  them  singly  to  a second 
dish  (B)  of  clean  water,  taking  each  from  the  bottom 
of  the  pile.  In  B they  are  allowed  to  soak  for  ten 
minutes,  the  bottom  one  being  continuously  brought 
to  the  top.  They  are  then  taken  back — singly,  as 
before — to  dish  A.  This  ten-minute  soak,  agitation  and 
transference  to  a second  dish  during  the  course  of  an 
hour  will  completely  free  them  from  hypo  and  ensure 
permanency. 

Amongst  the  enormous  variety  of  print  washers, 
really  eflScient  machines  are  rare,  especially  those 
capable  of  dealing  with  large  prints.  The  efficiency 
of  a washer  is  to  be  judged  by  how  far  it  permits  the 
complete  change  of  the  water  without  endangering 
the  prints  by  tearing  or  without  allowing  them  to  clot 
together.  The  best  plan  is  to  confine  them  in  a series 
of  dishes  through  which  a stream  of  water  passes  or 
which  is  placed  in  a box  which  is  alternately  filled 
and  exhausted  by  a siphon.  Such  a washer  is  easily 
made,  and  it  is  the  only  kind  in  which  a number  of 
large  prints  can  be  satisfactorily  washed. 

To  set  a negative  to  dry  just  as  it  comes  out  of  the 
washing  tank  is  not  good  practice.  Many  wash  waters 
are  hard  and  leave  a white  (calcareous)  deposit  which, 
though  it  may  do  no  harm,  is  untidy  and  may  give 
rise  to  patches  should  the  negative  be  intensified. 
Moreover,  drops  of  water  cling  here  and  there  and 
make  places  which  are  much  longer  in  drying.  There- 
fore, having  carefully  rinsed  the  negative  under  the 
tap,  gently  mop  the  gelatine  surface  with  a soft  piece 

56 


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of  cambric  or  absorbent  cotton  until  it  is  surface-dry 
all  over. 

The  rapidity  with  which  a gelatine  film  dries  de- 
pends on  two  things:  (1)  the  dryness  of  the  air  in 
contact  with  it  and  (2)  the  temperature  of  the  air. 
The  greatest  rapidity  is  gained  by  a combination  of 
these  two  conditions.  The  atmosphere,  remember, 
always  contains  moisture,  and  the  warmer  the  air  the 
more  moisture  it  can  contain.  What  we  want  is  dry, 
warm  air,  and  by  the  “dryness”  of  air  is  to  be  under- 
stood air  which  contains  very  little  moisture  compared 
with  the  quantity  which  it  can  (at  its  temperature) 
take  up.  Thus  the  air  in  a warm  room  may  be  drier 
than  the  atmosphere  out  of  doors  because,  though 
containing  exactly  the  same  weight  of  water  per  cubic 
foot,  the  warm  interior  air  can  take  up  more  water 
than  the  colder  external  air.  These  facts  ought  to  be 
borne  in  mind.  They  will  save  the  amateur  from  doing 
some  of  the  absurd  things  which  in  ignorance  of  them 
he  sometimes  attempts,  such  as  putting  negatives  to 
dry  in  a damp  dark-room  simply  because  it  is  warm. 

In  a confined  space  the  moisture  from  a negative 
will  saturate  the  air  with  moisture,  and  so  checks 
drying.  Hence  the  first  condition  is  to  get  a constant 
change  of  air.  If  this  is  warm  air,  all  the  better.  If  it 
is  filtered  from  floating  particles  of  matter,  better  still. 

About  the  worst  thing  on  which  to  dry  negatives 
are  the  racks  sold  for  this  purpose,  i.  e.,  if  they  are 
anywhere  near  being  fully  loaded.  About  the  best 
plan,  on  the  other  hand,  requires  no  special  apparatus. 
Drive  into  a convenient  wall  (or  into  a large  board 
which  can  be  reared  up  somewhere)  a number  of  iron 
nails  in  pairs,  the  two  nails  being  driven  in  at  a dis- 

57 


DARK-ROOM  WORK 


tance  apart  about  equal  to  the  shorter  side  of  the 
negative.  The  negative  is  laid  on  these  nails  (see 
Fig.  22).  If  it  is  placed  film  upwards  drying  takes 
place  more  rapidly;  if  film  downwards,  however,  there 
is  less  chance  of  dust  settling.  In  order  to  expedite 
drying  it  is  a good  plan  to  place  these  home-made  racks 
some  few  feet  from  the  floor,  and  also  to  arrange  an 
oil  stove  somewhere  near  at 
hand.  The  current  of  heated 
air  and  products  of  combus- 
tion will  greatly  decrease  the 
time  of  drying.  A more  com- 
pact arrangement  (of  which 
there  are  commercial  forms) 
is  one  in  which  the  plates  are 
set  on  a vertical  rack,  and  a 
current  of  warm  gases  caused 
to  ascend  over  them  by  means 
of  a row  of  tiny  gas  jets  in 
the  chamber  on  which  the 
rack  is  built.  This  is  easily 
made,  and  it  is  well  to  cover 
over  the  upper  rack  with  a 
framework  of  fine  wire  gauze, 
the  floor  being  likewise  cov- 
ered with  the  same  material.  Floating  specks  of  dirt 
are  thus  filtered  out. 

There  are  one  or  two  ways  of  drying  a negative 
rapidly — in  a minute  or  two — which  deserve  to  be 
mentioned.  The  first  is  by  wood  alcohol.  If  only  a 
single  negative  is  being  handled,  simply  place  it  for 
5 minutes  or  so  in  the  alcohol,  rocking  occasionally, 
and  on  removal  stand  it  up  to  dry,  which  it  will  do  in 

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DARK-ROOM  WORK 


a few  seconds.  But  if  a large  number  of  plates  are 
being  done,  it  is  necessary  (to  avoid  great  waste  of 
alcohol)  to  use  two  or  three  baths,  for  this  reason: 
The  first  bath  gradually  becomes  weaker  (more 
watery)  owing  to  the  accumulation  of  the  water  from 
the  films.  In  this  state  it  cannot  do  more  than  produce 
a plate  which  still  contains  a certain  proportion  of 
water,  and  which,  though  it  becomes  apparently  dry 
in  a few  seconds,  remains  sticky  for  a very  much  longer 
period.  By  draining  off  this  first  water-diluted  spirit, 
and  placing  in  a second  bath,  the  proportion  of  water 
in  the  film  is  reduced  to  a negligible  quantity  and  the 
films  dry  at  once  hard  and  clean.  Tanks  in  which  the 
plates  are  held  vertically  are  the  bes1;  for  the  purpose, 
an,d  when  not  in  use  should  be  kept  covered.  As  soon 
as  the  second  bath  begins  to  yield  tacky  negatives, 
another  should  be  installed.  The  first  may  either  be 
kept  in  hand  until  it  is  useless  or  at  once  discarded. 
The  latter  is  more  economical,  considering  the  time 
and  trouble  involved. 

Place  the  negative  in  a bath  of  formalin  (1  vol.) 
and  water  (9  vols.)  for  a few  minutes  and  rinse  under 
the  tap  afterwards.  The  film  is  now  hard  enough  to 
withstand  drying  at  practically  any  heat  which  the 
hand  holding  the  plate  can  bear.  Alum,  chrome  alum 
and  the  other  hardening  agents  can  be  used,  but  they 
require  more  washing  after  use  and  do  not  act  so 
vigorously  as  formalin. 

If  the  surface  moisture  be  mopped  off  the  negative 
with  a piece  of  cambric  or  fiuffless  blotting  paper,  a 
roller  squeegee  and  gentle  pressure  being  used,  it  is 
quite  possible  to  carefully  dry  the  negative  over  a 
gas  stove  or  before  a fire  without  the  aid  of  a previous 

59 


DARK-ROOM  WORK 


hardening  solution.  Some  plates  are  better  than  others 
in  this  respect;  with  those  containing  soft  gelatine 
(i.  e.,  plates  which  develop  quickly)  it  is  often  very 
risky.  Frequently,  however,  it  is  quite  safe,  and  it 
will  be  noticed  that  the  tendency  of  the  operation  is 
to  give  a ‘‘sparkle”  to  the  negative — an  advantage 
or  disadvantage,  according  to  circumstances. 

Roll  films  are  best  dried  by  suspending  the  strip  of 
film  from  a metal  clip  in  a current  of  cool,  dry  air. 
Cut  films  and  film  packs  are  most  conveniently  dried 
by  hanging  them  on  a line  with  pins  at  the  two  top 
corners  in  a current  of  air. 

The  life  of  the  negative  is  constantly  menaced  by 
breakage,  either  of  the  film  or  its  support.  Glass  is 
a brittle  substance  and  is  consequently  liable  to  break- 
ages, partial  or  complete.  The  breakage,  when  it 
occurs,  may  seem  irremediable,  but  seldom  is.  First, 
as  to  glass  negatives.  Sometimes,  when  the  negative 
has  been  developed  and  dried,  scratches  on  the  glass 
sides  are  seen.  These,  if  neglected,  will  print  through 
and  mar  the  image.  The  scratches  should  be  stopped 
out  with  a transparent  substance.  This  can  be  done 
by  cleaning  the  scratches  and  filling  them  up  with 
Canada  balsam,  thinned  down  with  benzole.  The 
Canada  balsam  is  to  be  had  at  any  drug-store.  When 
the  balsam  has  dried,  the  negative  should  print  through 
as  usual,  without  markings.  If  the  negative  is  broken 
in  several  pieces,  one  way  to  mend  it  is  by  mounting 
the  pieces  upon  clean  glass,  fitting  them  accurately 
together  and  exposing  for  a positive.  Retouching 
the  positive  will  remove  the  marks;  after  which  a nega- 
tive can  be  made  from  it. 

Jiut  the  defect  being  of  common  occurrence,  some 
CO 


DARK-ROOM  WORK 


more  effective  method  of  remedying  is  required.  The 
glass  of  the  plate  may  have  been  cracked  before  exposure 
and  development.  To  detach  the  film  from  the  broken 
support,  one  plan  is  to  soak  the  negative  for  twenty- 
four  hours  in  a cold  saturated  solution  of  washing  soda. 
This  will  soften  the  film,  which  can  be  peeled  off  the 
glass  untorn.  Then  soak  for  two  or  three  hours  in  plain 
water.  This  expands  the  film.  To  reduce  to  the 
original  size,  soak  in  a bath  of  alcohol,  which  will  re- 
duce the  film  to  the  original  size  and  toughen  it.  Then 
transfer  to  a clean  glass  plate  to  which  it  should  adhere. 
A fine  line  in  the  negative  may  still  exist,  due  to  the 
glass  having  been  cracked  before  development;  this 
mark  can  be  touched  out  on  the  print.  Another  plan 
is  to  prepare  the  following  solutions:  (1)  Fluoride  of 
sodium,  1-2  ounce;  water,  16  ounces;  cork  the  bottle  and 
shake  well.  (2)  Powdered  citric  acid,  1 ounce;  water, 
16  ounces;  cork  and  shake  well.  Have  at  hand  a clean 
glass  plate  larger  than  the  negative,  in  a tray  of  clean 
cold  water.  If  a half-plate  negative  is  being  stripped, 
a 5x7  dish  and  sheet  of  glass  are  necessary.  To  strip 
the  film  take  4 ounces  of  No.  1 solution  in  a tray  of  hard 
rubber  (which  is  impermeable  to  compounds  of  hydro- 
fluoric acid  formed  in  the  mixture) ; then  add  4 ounces 
of  No.  2.  Rock  the  mixture,  then  immerse  the  nega- 
tive, film  side  uppermost,  rock  the  tray  endwise  and 
crosswise,  allow  to  stand  for  half  a minute,  then  rock 
again.  The  film  will  slightly  frill  at  the  edges;  with  the 
forefinger  and  thumb  of  each  hand  lift  the  film  clean 
off  the  cracked  support,  place  in  the  water  above  the 
clean  glass  plate,  lift  the  plate  by  the  two  top  corners 
and  adjust  the  film  so  as  to  leave  a clean  margin  all 
round.  Lift  the  plate  and  film  together  and  drain. 


DARK-ROOM  WORK 


Lay  the  plate  in  a horizontal  position  and  adjust  the 
film  so  that  there  are  no  air-bubbles.  After  draining, 
allow  the  transferred  film  to  remain  in  a horizontal 
position  to  dry.  In  place  of  the  sodium  fluoride 
mixture,  formalin  is  used  by  some  workers.  Solution 
A:  Caustic  soda,  ten  per  cent  solution,  1-2  ounce; 
formalin  solution,  1-4  ounce;  water,  5 ounces.  Solution 
B:  Hydrochloric  acid,  C.  P.,  1 drachm;  water,  8 
ounces.  By  this  method,  if  the  negative  is  varnished 
or  retouched,  the  coating  should  be  rubbed  off  with 
alcohol  or  turpentine.  Soak  the  film  in  plain  water  to 
soften  it,  but  before  this,  with  a knife  and  a safe  edge, 
scratch  a line  through  the  film  to  the  glass,  around  the 
four  sides  of  the  negative,  close  to  the  edges.  This 
will  facilitate  stripping.  After  soaking  in  water  for 
half  an  hour,  immerse  plate  in  solution  A for  five  min- 
utes, rinse  and  transfer  to  solution  B for  five  minutes. 
Rinse  well  and  place  on  table,  face  up,  ready  for  strip- 
ping. Dampen  a clean  sheet  of  writing-paper  large 
enough  to  lap  over  the  plate  all  around,  lay  this  on  the 
film  and  cover  with  a blotter.  Take  a knife  and  start 
a corner  of  the  film  by  gently  lifting  it  up  with  the  finger. 
A gelatine-coated  plate  should  be  ready.  To  prepare 
the  coating,  soak  1 ounce  of  gelatine  in  16  ounces  of 
water  until  softened,  then  dissolve  by  heat.  Then  add 
chrome  alum,  20  grains,  dissolved  in  1 ounce  of  warm 
water,  add  gradually  to  the  gelatine  solution,  stirring 
to  prevent  precipitation.  The  glass  plate  should  be 
immersed  in  this  solution  while  warm  and  then  drained 
and  dried.  Lower  the  film  into  position  on  the  new  sup- 
port and  rub  into  contact  under  a blotter.  Remove 
the  paj)cr  and  dal)  out  any  bubbles  that  may  remain 
between  the  films. 


